Http client error code

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This is a list of Hypertext Transfer Protocol (HTTP) response status codes. Status codes are issued by a server in response to a client’s request made to the server. It includes codes from IETF Request for Comments (RFCs), other specifications, and some additional codes used in some common applications of the HTTP. The first digit of the status code specifies one of five standard classes of responses. The optional message phrases shown are typical, but any human-readable alternative may be provided, or none at all.

Unless otherwise stated, the status code is part of the HTTP standard (RFC 9110).

The Internet Assigned Numbers Authority (IANA) maintains the official registry of HTTP status codes.^[1]

All HTTP response status codes are separated into five classes or categories. The first digit of the status code defines the class of response, while the last two digits do not have any classifying or categorization role. There are five classes defined by the standard:

• 1xx informational response – the request was received, continuing process
• 2xx successful – the request was successfully received, understood, and accepted
• 3xx redirection – further action needs to be taken in order to complete the request
• 4xx client error – the request contains bad syntax or cannot be fulfilled
• 5xx server error – the server failed to fulfil an apparently valid request

1xx informational response

An informational response indicates that the request was received and understood. It is issued on a provisional basis while request processing continues. It alerts the client to wait for a final response. The message consists only of the status line and optional header fields, and is terminated by an empty line. As the HTTP/1.0 standard did not define any 1xx status codes, servers must not^{[note 1]} send a 1xx response to an HTTP/1.0 compliant client except under experimental conditions.

100 Continue

The server has received the request headers and the client should proceed to send the request body (in the case of a request for which a body needs to be sent; for example, a POST request). Sending a large request body to a server after a request has been rejected for inappropriate headers would be inefficient. To have a server check the request’s headers, a client must send Expect: 100-continue as a header in its initial request and receive a 100 Continue status code in response before sending the body. If the client receives an error code such as 403 (Forbidden) or 405 (Method Not Allowed) then it should not send the request’s body. The response 417 Expectation Failed indicates that the request should be repeated without the Expect header as it indicates that the server does not support expectations (this is the case, for example, of HTTP/1.0 servers).^[2]

101 Switching Protocols

The requester has asked the server to switch protocols and the server has agreed to do so.

102 Processing (WebDAV; RFC 2518)

A WebDAV request may contain many sub-requests involving file operations, requiring a long time to complete the request. This code indicates that the server has received and is processing the request, but no response is available yet.^[3] This prevents the client from timing out and assuming the request was lost.

103 Early Hints (RFC 8297)

Used to return some response headers before final HTTP message.^[4]

2xx success

This class of status codes indicates the action requested by the client was received, understood, and accepted.^[1]

200 OK

Standard response for successful HTTP requests. The actual response will depend on the request method used. In a GET request, the response will contain an entity corresponding to the requested resource. In a POST request, the response will contain an entity describing or containing the result of the action.

201 Created

The request has been fulfilled, resulting in the creation of a new resource.^[5]

202 Accepted

The request has been accepted for processing, but the processing has not been completed. The request might or might not be eventually acted upon, and may be disallowed when processing occurs.

203 Non-Authoritative Information (since HTTP/1.1)

The server is a transforming proxy (e.g. a Web accelerator) that received a 200 OK from its origin, but is returning a modified version of the origin’s response.^[6][7]

204 No Content

The server successfully processed the request, and is not returning any content.

205 Reset Content

The server successfully processed the request, asks that the requester reset its document view, and is not returning any content.

206 Partial Content

The server is delivering only part of the resource (byte serving) due to a range header sent by the client. The range header is used by HTTP clients to enable resuming of interrupted downloads, or split a download into multiple simultaneous streams.

207 Multi-Status (WebDAV; RFC 4918)

The message body that follows is by default an XML message and can contain a number of separate response codes, depending on how many sub-requests were made.^[8]

208 Already Reported (WebDAV; RFC 5842)

The members of a DAV binding have already been enumerated in a preceding part of the (multistatus) response, and are not being included again.

226 IM Used (RFC 3229)

The server has fulfilled a request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance.^[9]

3xx redirection

This class of status code indicates the client must take additional action to complete the request. Many of these status codes are used in URL redirection.^[1]

A user agent may carry out the additional action with no user interaction only if the method used in the second request is GET or HEAD. A user agent may automatically redirect a request. A user agent should detect and intervene to prevent cyclical redirects.^[10]

300 Multiple Choices

Indicates multiple options for the resource from which the client may choose (via agent-driven content negotiation). For example, this code could be used to present multiple video format options, to list files with different filename extensions, or to suggest word-sense disambiguation.

301 Moved Permanently

This and all future requests should be directed to the given URI.

302 Found (Previously «Moved temporarily»)

Tells the client to look at (browse to) another URL. The HTTP/1.0 specification (RFC 1945) required the client to perform a temporary redirect with the same method (the original describing phrase was «Moved Temporarily»),^[11] but popular browsers implemented 302 redirects by changing the method to GET. Therefore, HTTP/1.1 added status codes 303 and 307 to distinguish between the two behaviours.^[10]

303 See Other (since HTTP/1.1)

The response to the request can be found under another URI using the GET method. When received in response to a POST (or PUT/DELETE), the client should presume that the server has received the data and should issue a new GET request to the given URI.

304 Not Modified

Indicates that the resource has not been modified since the version specified by the request headers If-Modified-Since or If-None-Match. In such case, there is no need to retransmit the resource since the client still has a previously-downloaded copy.

305 Use Proxy (since HTTP/1.1)

The requested resource is available only through a proxy, the address for which is provided in the response. For security reasons, many HTTP clients (such as Mozilla Firefox and Internet Explorer) do not obey this status code.

306 Switch Proxy

No longer used. Originally meant «Subsequent requests should use the specified proxy.»

307 Temporary Redirect (since HTTP/1.1)

In this case, the request should be repeated with another URI; however, future requests should still use the original URI. In contrast to how 302 was historically implemented, the request method is not allowed to be changed when reissuing the original request. For example, a POST request should be repeated using another POST request.

308 Permanent Redirect

This and all future requests should be directed to the given URI. 308 parallel the behaviour of 301, but does not allow the HTTP method to change. So, for example, submitting a form to a permanently redirected resource may continue smoothly.

4xx client errors

This class of status code is intended for situations in which the error seems to have been caused by the client. Except when responding to a HEAD request, the server should include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition. These status codes are applicable to any request method. User agents should display any included entity to the user.

400 Bad Request

The server cannot or will not process the request due to an apparent client error (e.g., malformed request syntax, size too large, invalid request message framing, or deceptive request routing).

401 Unauthorized

Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource. See Basic access authentication and Digest access authentication. 401 semantically means «unauthorised», the user does not have valid authentication credentials for the target resource.

Some sites incorrectly issue HTTP 401 when an IP address is banned from the website (usually the website domain) and that specific address is refused permission to access a website.^{[citation needed]}

402 Payment Required

Reserved for future use. The original intention was that this code might be used as part of some form of digital cash or micropayment scheme, as proposed, for example, by GNU Taler,^[13] but that has not yet happened, and this code is not widely used. Google Developers API uses this status if a particular developer has exceeded the daily limit on requests.^[14] Sipgate uses this code if an account does not have sufficient funds to start a call.^[15] Shopify uses this code when the store has not paid their fees and is temporarily disabled.^[16] Stripe uses this code for failed payments where parameters were correct, for example blocked fraudulent payments.^[17]

403 Forbidden

The request contained valid data and was understood by the server, but the server is refusing action. This may be due to the user not having the necessary permissions for a resource or needing an account of some sort, or attempting a prohibited action (e.g. creating a duplicate record where only one is allowed). This code is also typically used if the request provided authentication by answering the WWW-Authenticate header field challenge, but the server did not accept that authentication. The request should not be repeated.

404 Not Found

The requested resource could not be found but may be available in the future. Subsequent requests by the client are permissible.

405 Method Not Allowed

A request method is not supported for the requested resource; for example, a GET request on a form that requires data to be presented via POST, or a PUT request on a read-only resource.

406 Not Acceptable

The requested resource is capable of generating only content not acceptable according to the Accept headers sent in the request. See Content negotiation.

407 Proxy Authentication Required

The client must first authenticate itself with the proxy.

408 Request Timeout

The server timed out waiting for the request. According to HTTP specifications: «The client did not produce a request within the time that the server was prepared to wait. The client MAY repeat the request without modifications at any later time.»

409 Conflict

Indicates that the request could not be processed because of conflict in the current state of the resource, such as an edit conflict between multiple simultaneous updates.

410 Gone

Indicates that the resource requested was previously in use but is no longer available and will not be available again. This should be used when a resource has been intentionally removed and the resource should be purged. Upon receiving a 410 status code, the client should not request the resource in the future. Clients such as search engines should remove the resource from their indices. Most use cases do not require clients and search engines to purge the resource, and a «404 Not Found» may be used instead.

411 Length Required

The request did not specify the length of its content, which is required by the requested resource.

412 Precondition Failed

The server does not meet one of the preconditions that the requester put on the request header fields.

413 Payload Too Large

The request is larger than the server is willing or able to process. Previously called «Request Entity Too Large» in RFC 2616.^[18]

414 URI Too Long

The URI provided was too long for the server to process. Often the result of too much data being encoded as a query-string of a GET request, in which case it should be converted to a POST request. Called «Request-URI Too Long» previously in RFC 2616.^[19]

415 Unsupported Media Type

The request entity has a media type which the server or resource does not support. For example, the client uploads an image as image/svg+xml, but the server requires that images use a different format.

416 Range Not Satisfiable

The client has asked for a portion of the file (byte serving), but the server cannot supply that portion. For example, if the client asked for a part of the file that lies beyond the end of the file. Called «Requested Range Not Satisfiable» previously RFC 2616.^[20]

417 Expectation Failed

The server cannot meet the requirements of the Expect request-header field.^[21]

418 I’m a teapot (RFC 2324, RFC 7168)

This code was defined in 1998 as one of the traditional IETF April Fools’ jokes, in RFC 2324, Hyper Text Coffee Pot Control Protocol, and is not expected to be implemented by actual HTTP servers. The RFC specifies this code should be returned by teapots requested to brew coffee.^[22] This HTTP status is used as an Easter egg in some websites, such as Google.com’s «I’m a teapot» easter egg.^[23][24][25] Sometimes, this status code is also used as a response to a blocked request, instead of the more appropriate 403 Forbidden.^[26][27]

421 Misdirected Request

The request was directed at a server that is not able to produce a response (for example because of connection reuse).

422 Unprocessable Entity

The request was well-formed but was unable to be followed due to semantic errors.^[8]

423 Locked (WebDAV; RFC 4918)

The resource that is being accessed is locked.^[8]

424 Failed Dependency (WebDAV; RFC 4918)

The request failed because it depended on another request and that request failed (e.g., a PROPPATCH).^[8]

425 Too Early (RFC 8470)

Indicates that the server is unwilling to risk processing a request that might be replayed.

426 Upgrade Required

The client should switch to a different protocol such as TLS/1.3, given in the Upgrade header field.

428 Precondition Required (RFC 6585)

The origin server requires the request to be conditional. Intended to prevent the ‘lost update’ problem, where a client GETs a resource’s state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict.^[28]

429 Too Many Requests (RFC 6585)

The user has sent too many requests in a given amount of time. Intended for use with rate-limiting schemes.^[28]

431 Request Header Fields Too Large (RFC 6585)

The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large.^[28]

451 Unavailable For Legal Reasons (RFC 7725)

A server operator has received a legal demand to deny access to a resource or to a set of resources that includes the requested resource.^[29] The code 451 was chosen as a reference to the novel Fahrenheit 451 (see the Acknowledgements in the RFC).

5xx server errors

The server failed to fulfil a request.

Response status codes beginning with the digit «5» indicate cases in which the server is aware that it has encountered an error or is otherwise incapable of performing the request. Except when responding to a HEAD request, the server should include an entity containing an explanation of the error situation, and indicate whether it is a temporary or permanent condition. Likewise, user agents should display any included entity to the user. These response codes are applicable to any request method.

500 Internal Server Error

A generic error message, given when an unexpected condition was encountered and no more specific message is suitable.

501 Not Implemented

The server either does not recognize the request method, or it lacks the ability to fulfil the request. Usually this implies future availability (e.g., a new feature of a web-service API).

502 Bad Gateway

The server was acting as a gateway or proxy and received an invalid response from the upstream server.

503 Service Unavailable

The server cannot handle the request (because it is overloaded or down for maintenance). Generally, this is a temporary state.^[30]

504 Gateway Timeout

The server was acting as a gateway or proxy and did not receive a timely response from the upstream server.

505 HTTP Version Not Supported

The server does not support the HTTP version used in the request.

506 Variant Also Negotiates (RFC 2295)

Transparent content negotiation for the request results in a circular reference.^[31]

507 Insufficient Storage (WebDAV; RFC 4918)

The server is unable to store the representation needed to complete the request.^[8]

508 Loop Detected (WebDAV; RFC 5842)

The server detected an infinite loop while processing the request (sent instead of 208 Already Reported).

510 Not Extended (RFC 2774)

Further extensions to the request are required for the server to fulfill it.^[32]

511 Network Authentication Required (RFC 6585)

The client needs to authenticate to gain network access. Intended for use by intercepting proxies used to control access to the network (e.g., «captive portals» used to require agreement to Terms of Service before granting full Internet access via a Wi-Fi hotspot).^[28]

Unofficial codes

The following codes are not specified by any standard.

419 Page Expired (Laravel Framework)

Used by the Laravel Framework when a CSRF Token is missing or expired.

420 Method Failure (Spring Framework)

A deprecated response used by the Spring Framework when a method has failed.^[33]

420 Enhance Your Calm (Twitter)

Returned by version 1 of the Twitter Search and Trends API when the client is being rate limited; versions 1.1 and later use the 429 Too Many Requests response code instead.^[34] The phrase «Enhance your calm» comes from the 1993 movie Demolition Man, and its association with this number is likely a reference to cannabis.^{[citation needed]}

430 Request Header Fields Too Large (Shopify)

Used by Shopify, instead of the 429 Too Many Requests response code, when too many URLs are requested within a certain time frame.^[35]

450 Blocked by Windows Parental Controls (Microsoft)

The Microsoft extension code indicated when Windows Parental Controls are turned on and are blocking access to the requested webpage.^[36]

498 Invalid Token (Esri)

Returned by ArcGIS for Server. Code 498 indicates an expired or otherwise invalid token.^[37]

499 Token Required (Esri)

Returned by ArcGIS for Server. Code 499 indicates that a token is required but was not submitted.^[37]

509 Bandwidth Limit Exceeded (Apache Web Server/cPanel)

The server has exceeded the bandwidth specified by the server administrator; this is often used by shared hosting providers to limit the bandwidth of customers.^[38]

529 Site is overloaded

Used by Qualys in the SSLLabs server testing API to signal that the site can’t process the request.^[39]

530 Site is frozen

Used by the Pantheon Systems web platform to indicate a site that has been frozen due to inactivity.^[40]

598 (Informal convention) Network read timeout error

Used by some HTTP proxies to signal a network read timeout behind the proxy to a client in front of the proxy.^[41]

599 Network Connect Timeout Error

An error used by some HTTP proxies to signal a network connect timeout behind the proxy to a client in front of the proxy.

Internet Information Services

Microsoft’s Internet Information Services (IIS) web server expands the 4xx error space to signal errors with the client’s request.

440 Login Time-out

The client’s session has expired and must log in again.^[42]

449 Retry With

The server cannot honour the request because the user has not provided the required information.^[43]

451 Redirect

Used in Exchange ActiveSync when either a more efficient server is available or the server cannot access the users’ mailbox.^[44] The client is expected to re-run the HTTP AutoDiscover operation to find a more appropriate server.^[45]

IIS sometimes uses additional decimal sub-codes for more specific information,^[46] however these sub-codes only appear in the response payload and in documentation, not in the place of an actual HTTP status code.

nginx

The nginx web server software expands the 4xx error space to signal issues with the client’s request.^[47][48]

444 No Response

Used internally^[49] to instruct the server to return no information to the client and close the connection immediately.

494 Request header too large

Client sent too large request or too long header line.

495 SSL Certificate Error

An expansion of the 400 Bad Request response code, used when the client has provided an invalid client certificate.

496 SSL Certificate Required

An expansion of the 400 Bad Request response code, used when a client certificate is required but not provided.

497 HTTP Request Sent to HTTPS Port

An expansion of the 400 Bad Request response code, used when the client has made a HTTP request to a port listening for HTTPS requests.

499 Client Closed Request

Used when the client has closed the request before the server could send a response.

Cloudflare

Cloudflare’s reverse proxy service expands the 5xx series of errors space to signal issues with the origin server.^[50]

520 Web Server Returned an Unknown Error

The origin server returned an empty, unknown, or unexpected response to Cloudflare.^[51]

521 Web Server Is Down

The origin server refused connections from Cloudflare. Security solutions at the origin may be blocking legitimate connections from certain Cloudflare IP addresses.

522 Connection Timed Out

Cloudflare timed out contacting the origin server.

523 Origin Is Unreachable

Cloudflare could not reach the origin server; for example, if the DNS records for the origin server are incorrect or missing.

524 A Timeout Occurred

Cloudflare was able to complete a TCP connection to the origin server, but did not receive a timely HTTP response.

525 SSL Handshake Failed

Cloudflare could not negotiate a SSL/TLS handshake with the origin server.

526 Invalid SSL Certificate

Cloudflare could not validate the SSL certificate on the origin web server. Also used by Cloud Foundry’s gorouter.

527 Railgun Error

Error 527 indicates an interrupted connection between Cloudflare and the origin server’s Railgun server.^[52]

530

Error 530 is returned along with a 1xxx error.^[53]

AWS Elastic Load Balancer

Amazon’s Elastic Load Balancing adds a few custom return codes

460

Client closed the connection with the load balancer before the idle timeout period elapsed. Typically when client timeout is sooner than the Elastic Load Balancer’s timeout.^[54]

463

The load balancer received an X-Forwarded-For request header with more than 30 IP addresses.^[54]

561 Unauthorized

An error around authentication returned by a server registered with a load balancer. You configured a listener rule to authenticate users, but the identity provider (IdP) returned an error code when authenticating the user.^[55]

Caching warning codes (obsoleted)

The following caching related warning codes were specified under RFC 7234. Unlike the other status codes above, these were not sent as the response status in the HTTP protocol, but as part of the «Warning» HTTP header.^[56][57]

Since this «Warning» header is often neither sent by servers nor acknowledged by clients, this header and its codes were obsoleted by the HTTP Working Group in 2022 with RFC 9111.^[58]

110 Response is Stale

The response provided by a cache is stale (the content’s age exceeds a maximum age set by a Cache-Control header or heuristically chosen lifetime).

111 Revalidation Failed

The cache was unable to validate the response, due to an inability to reach the origin server.

112 Disconnected Operation

The cache is intentionally disconnected from the rest of the network.

113 Heuristic Expiration

The cache heuristically chose a freshness lifetime greater than 24 hours and the response’s age is greater than 24 hours.

199 Miscellaneous Warning

Arbitrary, non-specific warning. The warning text may be logged or presented to the user.

214 Transformation Applied

Added by a proxy if it applies any transformation to the representation, such as changing the content encoding, media type or the like.

299 Miscellaneous Persistent Warning

Same as 199, but indicating a persistent warning.

See also

• Custom error pages
• List of FTP server return codes
• List of HTTP header fields
• List of SMTP server return codes
• Common Log Format

Explanatory notes

References

External links

• «RFC 9110: HTTP Semantics and Content, Section 15 «Status Codes»«.
• Hypertext Transfer Protocol (HTTP) Status Code Registry

HTTP response status codes indicate whether a specific HTTP request has been successfully completed.
Responses are grouped in five classes:

1. Informational responses (100 – 199)
2. Successful responses (200 – 299)
3. Redirection messages (300 – 399)
4. Client error responses (400 – 499)
5. Server error responses (500 – 599)

The status codes listed below are defined by RFC 9110.

Note: If you receive a response that is not in this list, it is a non-standard response, possibly custom to the server’s software.

Information responses

100 Continue

This interim response indicates that the client should continue the request or ignore the response if the request is already finished.

101 Switching Protocols

This code is sent in response to an Upgrade request header from the client and indicates the protocol the server is switching to.

102 Processing (WebDAV)

This code indicates that the server has received and is processing the request, but no response is available yet.

103 Early Hints

This status code is primarily intended to be used with the Link header, letting the user agent start preloading resources while the server prepares a response.

Successful responses

200 OK

The request succeeded. The result meaning of «success» depends on the HTTP method:

• GET: The resource has been fetched and transmitted in the message body.
• HEAD: The representation headers are included in the response without any message body.
• PUT or POST: The resource describing the result of the action is transmitted in the message body.
• TRACE: The message body contains the request message as received by the server.

201 Created

The request succeeded, and a new resource was created as a result. This is typically the response sent after POST requests, or some PUT requests.

202 Accepted

The request has been received but not yet acted upon.
It is noncommittal, since there is no way in HTTP to later send an asynchronous response indicating the outcome of the request.
It is intended for cases where another process or server handles the request, or for batch processing.

This response code means the returned metadata is not exactly the same as is available from the origin server, but is collected from a local or a third-party copy.
This is mostly used for mirrors or backups of another resource.
Except for that specific case, the 200 OK response is preferred to this status.

204 No Content

There is no content to send for this request, but the headers may be useful.
The user agent may update its cached headers for this resource with the new ones.

205 Reset Content

Tells the user agent to reset the document which sent this request.

206 Partial Content

This response code is used when the Range header is sent from the client to request only part of a resource.

207 Multi-Status (WebDAV)

Conveys information about multiple resources, for situations where multiple status codes might be appropriate.

208 Already Reported (WebDAV)

Used inside a <dav:propstat> response element to avoid repeatedly enumerating the internal members of multiple bindings to the same collection.

226 IM Used (HTTP Delta encoding)

The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance.

Redirection messages

300 Multiple Choices

The request has more than one possible response. The user agent or user should choose one of them. (There is no standardized way of choosing one of the responses, but HTML links to the possibilities are recommended so the user can pick.)

301 Moved Permanently

The URL of the requested resource has been changed permanently. The new URL is given in the response.

302 Found

This response code means that the URI of requested resource has been changed temporarily.
Further changes in the URI might be made in the future. Therefore, this same URI should be used by the client in future requests.

303 See Other

The server sent this response to direct the client to get the requested resource at another URI with a GET request.

304 Not Modified

This is used for caching purposes.
It tells the client that the response has not been modified, so the client can continue to use the same cached version of the response.

305 Use Proxy
Deprecated

Defined in a previous version of the HTTP specification to indicate that a requested response must be accessed by a proxy.
It has been deprecated due to security concerns regarding in-band configuration of a proxy.

306 unused

This response code is no longer used; it is just reserved. It was used in a previous version of the HTTP/1.1 specification.

307 Temporary Redirect

The server sends this response to direct the client to get the requested resource at another URI with same method that was used in the prior request.
This has the same semantics as the 302 Found HTTP response code, with the exception that the user agent must not change the HTTP method used: if a POST was used in the first request, a POST must be used in the second request.

308 Permanent Redirect

This means that the resource is now permanently located at another URI, specified by the Location: HTTP Response header.
This has the same semantics as the 301 Moved Permanently HTTP response code, with the exception that the user agent must not change the HTTP method used: if a POST was used in the first request, a POST must be used in the second request.

Client error responses

400 Bad Request

The server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).

401 Unauthorized

Although the HTTP standard specifies «unauthorized», semantically this response means «unauthenticated».
That is, the client must authenticate itself to get the requested response.

402 Payment Required
Experimental

This response code is reserved for future use.
The initial aim for creating this code was using it for digital payment systems, however this status code is used very rarely and no standard convention exists.

403 Forbidden

The client does not have access rights to the content; that is, it is unauthorized, so the server is refusing to give the requested resource.
Unlike 401 Unauthorized, the client’s identity is known to the server.

404 Not Found

The server cannot find the requested resource.
In the browser, this means the URL is not recognized.
In an API, this can also mean that the endpoint is valid but the resource itself does not exist.
Servers may also send this response instead of 403 Forbidden to hide the existence of a resource from an unauthorized client.
This response code is probably the most well known due to its frequent occurrence on the web.

405 Method Not Allowed

The request method is known by the server but is not supported by the target resource.
For example, an API may not allow calling DELETE to remove a resource.

406 Not Acceptable

This response is sent when the web server, after performing server-driven content negotiation, doesn’t find any content that conforms to the criteria given by the user agent.

407 Proxy Authentication Required

This is similar to 401 Unauthorized but authentication is needed to be done by a proxy.

408 Request Timeout

This response is sent on an idle connection by some servers, even without any previous request by the client.
It means that the server would like to shut down this unused connection.
This response is used much more since some browsers, like Chrome, Firefox 27+, or IE9, use HTTP pre-connection mechanisms to speed up surfing.
Also note that some servers merely shut down the connection without sending this message.

409 Conflict

This response is sent when a request conflicts with the current state of the server.

410 Gone

This response is sent when the requested content has been permanently deleted from server, with no forwarding address.
Clients are expected to remove their caches and links to the resource.
The HTTP specification intends this status code to be used for «limited-time, promotional services».
APIs should not feel compelled to indicate resources that have been deleted with this status code.

411 Length Required

Server rejected the request because the Content-Length header field is not defined and the server requires it.

412 Precondition Failed

The client has indicated preconditions in its headers which the server does not meet.

413 Payload Too Large

Request entity is larger than limits defined by server.
The server might close the connection or return an Retry-After header field.

414 URI Too Long

The URI requested by the client is longer than the server is willing to interpret.

415 Unsupported Media Type

The media format of the requested data is not supported by the server, so the server is rejecting the request.

416 Range Not Satisfiable

The range specified by the Range header field in the request cannot be fulfilled.
It’s possible that the range is outside the size of the target URI’s data.

417 Expectation Failed

This response code means the expectation indicated by the Expect request header field cannot be met by the server.

418 I'm a teapot

The server refuses the attempt to brew coffee with a teapot.

421 Misdirected Request

The request was directed at a server that is not able to produce a response.
This can be sent by a server that is not configured to produce responses for the combination of scheme and authority that are included in the request URI.

422 Unprocessable Entity (WebDAV)

The request was well-formed but was unable to be followed due to semantic errors.

423 Locked (WebDAV)

The resource that is being accessed is locked.

424 Failed Dependency (WebDAV)

The request failed due to failure of a previous request.

425 Too Early
Experimental

Indicates that the server is unwilling to risk processing a request that might be replayed.

426 Upgrade Required

The server refuses to perform the request using the current protocol but might be willing to do so after the client upgrades to a different protocol.
The server sends an Upgrade header in a 426 response to indicate the required protocol(s).

428 Precondition Required

The origin server requires the request to be conditional.
This response is intended to prevent the ‘lost update’ problem, where a client GETs a resource’s state, modifies it and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict.

429 Too Many Requests

The user has sent too many requests in a given amount of time («rate limiting»).

The server is unwilling to process the request because its header fields are too large.
The request may be resubmitted after reducing the size of the request header fields.

451 Unavailable For Legal Reasons

The user agent requested a resource that cannot legally be provided, such as a web page censored by a government.

Server error responses

500 Internal Server Error

The server has encountered a situation it does not know how to handle.

501 Not Implemented

The request method is not supported by the server and cannot be handled. The only methods that servers are required to support (and therefore that must not return this code) are GET and HEAD.

502 Bad Gateway

This error response means that the server, while working as a gateway to get a response needed to handle the request, got an invalid response.

503 Service Unavailable

The server is not ready to handle the request.
Common causes are a server that is down for maintenance or that is overloaded.
Note that together with this response, a user-friendly page explaining the problem should be sent.
This response should be used for temporary conditions and the Retry-After HTTP header should, if possible, contain the estimated time before the recovery of the service.
The webmaster must also take care about the caching-related headers that are sent along with this response, as these temporary condition responses should usually not be cached.

504 Gateway Timeout

This error response is given when the server is acting as a gateway and cannot get a response in time.

505 HTTP Version Not Supported

The HTTP version used in the request is not supported by the server.

506 Variant Also Negotiates

The server has an internal configuration error: the chosen variant resource is configured to engage in transparent content negotiation itself, and is therefore not a proper end point in the negotiation process.

507 Insufficient Storage (WebDAV)

The method could not be performed on the resource because the server is unable to store the representation needed to successfully complete the request.

508 Loop Detected (WebDAV)

The server detected an infinite loop while processing the request.

510 Not Extended

Further extensions to the request are required for the server to fulfill it.

511 Network Authentication Required

Indicates that the client needs to authenticate to gain network access.

Browser compatibility

BCD tables only load in the browser

See also

REST APIs use the Status-Line part of an HTTP response message to inform clients of their request’s overarching result. RFC 2616 defines the Status-Line syntax as shown below:

Status-Line = HTTP-Version SP Status-Code SP Reason-Phrase CRLF

HTTP defines these standard status codes that can be used to convey the results of a client’s request. The status codes are divided into five categories.

• 1xx: Informational – Communicates transfer protocol-level information.
• 2xx: Success – Indicates that the client’s request was accepted successfully.
• 3xx: Redirection – Indicates that the client must take some additional action in order to complete their request.
• 4xx: Client Error – This category of error status codes points the finger at clients.
• 5xx: Server Error – The server takes responsibility for these error status codes.

1xx Status Codes [Informational]

Status Code	Description
100 Continue	An interim response. Indicates to the client that the initial part of the request has been received and has not yet been rejected by the server. The client SHOULD continue by sending the remainder of the request or, if the request has already been completed, ignore this response. The server MUST send a final response after the request has been completed.
101 Switching Protocol	Sent in response to an Upgrade request header from the client, and indicates the protocol the server is switching to.
102 Processing (WebDAV)	Indicates that the server has received and is processing the request, but no response is available yet.
103 Early Hints	Primarily intended to be used with the Link header. It suggests the user agent start preloading the resources while the server prepares a final response.

2xx Status Codes [Success]

Status Code	Description
200 OK	Indicates that the request has succeeded.
201 Created	Indicates that the request has succeeded and a new resource has been created as a result.
202 Accepted	Indicates that the request has been received but not completed yet. It is typically used in log running requests and batch processing.
203 Non-Authoritative Information	Indicates that the returned metainformation in the entity-header is not the definitive set as available from the origin server, but is gathered from a local or a third-party copy. The set presented MAY be a subset or superset of the original version.
204 No Content	The server has fulfilled the request but does not need to return a response body. The server may return the updated meta information.
205 Reset Content	Indicates the client to reset the document which sent this request.
206 Partial Content	It is used when the Range header is sent from the client to request only part of a resource.
207 Multi-Status (WebDAV)	An indicator to a client that multiple operations happened, and that the status for each operation can be found in the body of the response.
208 Already Reported (WebDAV)	Allows a client to tell the server that the same resource (with the same binding) was mentioned earlier. It never appears as a true HTTP response code in the status line, and only appears in bodies.
226 IM Used	The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance.

3xx Status Codes [Redirection]

Status Code	Description
300 Multiple Choices	The request has more than one possible response. The user-agent or user should choose one of them.
301 Moved Permanently	The URL of the requested resource has been changed permanently. The new URL is given by the Location header field in the response. This response is cacheable unless indicated otherwise.
302 Found	The URL of the requested resource has been changed temporarily. The new URL is given by the Location field in the response. This response is only cacheable if indicated by a Cache-Control or Expires header field.
303 See Other	The response can be found under a different URI and SHOULD be retrieved using a GET method on that resource.
304 Not Modified	Indicates the client that the response has not been modified, so the client can continue to use the same cached version of the response.
305 Use Proxy (Deprecated)	Indicates that a requested response must be accessed by a proxy.
306 (Unused)	It is a reserved status code and is not used anymore.
307 Temporary Redirect	Indicates the client to get the requested resource at another URI with same method that was used in the prior request. It is similar to 302 Found with one exception that the same HTTP method will be used that was used in the prior request.
308 Permanent Redirect (experimental)	Indicates that the resource is now permanently located at another URI, specified by the Location header. It is similar to 301 Moved Permanently with one exception that the same HTTP method will be used that was used in the prior request.

4xx Status Codes (Client Error)

Status Code	Description
400 Bad Request	The request could not be understood by the server due to incorrect syntax. The client SHOULD NOT repeat the request without modifications.
401 Unauthorized	Indicates that the request requires user authentication information. The client MAY repeat the request with a suitable Authorization header field
402 Payment Required (Experimental)	Reserved for future use. It is aimed for using in the digital payment systems.
403 Forbidden	Unauthorized request. The client does not have access rights to the content. Unlike 401, the client’s identity is known to the server.
404 Not Found	The server can not find the requested resource.
405 Method Not Allowed	The request HTTP method is known by the server but has been disabled and cannot be used for that resource.
406 Not Acceptable	The server doesn’t find any content that conforms to the criteria given by the user agent in the Accept header sent in the request.
407 Proxy Authentication Required	Indicates that the client must first authenticate itself with the proxy.
408 Request Timeout	Indicates that the server did not receive a complete request from the client within the server’s allotted timeout period.
409 Conflict	The request could not be completed due to a conflict with the current state of the resource.
410 Gone	The requested resource is no longer available at the server.
411 Length Required	The server refuses to accept the request without a defined Content- Length. The client MAY repeat the request if it adds a valid Content-Length header field.
412 Precondition Failed	The client has indicated preconditions in its headers which the server does not meet.
413 Request Entity Too Large	Request entity is larger than limits defined by server.
414 Request-URI Too Long	The URI requested by the client is longer than the server can interpret.
415 Unsupported Media Type	The media-type in Content-type of the request is not supported by the server.
416 Requested Range Not Satisfiable	The range specified by the Range header field in the request can’t be fulfilled.
417 Expectation Failed	The expectation indicated by the Expect request header field can’t be met by the server.
418 I’m a teapot (RFC 2324)	It was defined as April’s lool joke and is not expected to be implemented by actual HTTP servers. (RFC 2324)
420 Enhance Your Calm (Twitter)	Returned by the Twitter Search and Trends API when the client is being rate limited.
422 Unprocessable Entity (WebDAV)	The server understands the content type and syntax of the request entity, but still server is unable to process the request for some reason.
423 Locked (WebDAV)	The resource that is being accessed is locked.
424 Failed Dependency (WebDAV)	The request failed due to failure of a previous request.
425 Too Early (WebDAV)	Indicates that the server is unwilling to risk processing a request that might be replayed.
426 Upgrade Required	The server refuses to perform the request. The server will process the request after the client upgrades to a different protocol.
428 Precondition Required	The origin server requires the request to be conditional.
429 Too Many Requests	The user has sent too many requests in a given amount of time (“rate limiting”).
431 Request Header Fields Too Large	The server is unwilling to process the request because its header fields are too large.
444 No Response (Nginx)	The Nginx server returns no information to the client and closes the connection.
449 Retry With (Microsoft)	The request should be retried after performing the appropriate action.
450 Blocked by Windows Parental Controls (Microsoft)	Windows Parental Controls are turned on and are blocking access to the given webpage.
451 Unavailable For Legal Reasons	The user-agent requested a resource that cannot legally be provided.
499 Client Closed Request (Nginx)	The connection is closed by the client while HTTP server is processing its request, making the server unable to send the HTTP header back.

5xx Status Codes (Server Error)

Status Code	Description
500 Internal Server Error	The server encountered an unexpected condition that prevented it from fulfilling the request.
501 Not Implemented	The HTTP method is not supported by the server and cannot be handled.
502 Bad Gateway	The server got an invalid response while working as a gateway to get the response needed to handle the request.
503 Service Unavailable	The server is not ready to handle the request.
504 Gateway Timeout	The server is acting as a gateway and cannot get a response in time for a request.
505 HTTP Version Not Supported (Experimental)	The HTTP version used in the request is not supported by the server.
506 Variant Also Negotiates (Experimental)	Indicates that the server has an internal configuration error: the chosen variant resource is configured to engage in transparent content negotiation itself, and is therefore not a proper endpoint in the negotiation process.
507 Insufficient Storage (WebDAV)	The method could not be performed on the resource because the server is unable to store the representation needed to successfully complete the request.
508 Loop Detected (WebDAV)	The server detected an infinite loop while processing the request.
510 Not Extended	Further extensions to the request are required for the server to fulfill it.
511 Network Authentication Required	Indicates that the client needs to authenticate to gain network access.

6. REST Specific HTTP Status Codes

200 (OK)

It indicates that the REST API successfully carried out whatever action the client requested and that no more specific code in the 2xx series is appropriate.

Unlike the 204 status code, a 200 response should include a response body. The information returned with the response is dependent on the method used in the request, for example:

• GET an entity corresponding to the requested resource is sent in the response;
• HEAD the entity-header fields corresponding to the requested resource are sent in the response without any message-body;
• POST an entity describing or containing the result of the action;
• TRACE an entity containing the request message as received by the end server.

201 (Created)

A REST API responds with the 201 status code whenever a resource is created inside a collection. There may also be times when a new resource is created as a result of some controller action, in which case 201 would also be an appropriate response.

The newly created resource can be referenced by the URI(s) returned in the entity of the response, with the most specific URI for the resource given by a Location header field.

The origin server MUST create the resource before returning the 201 status code. If the action cannot be carried out immediately, the server SHOULD respond with a 202 (Accepted) response instead.

202 (Accepted)

A 202 response is typically used for actions that take a long while to process. It indicates that the request has been accepted for processing, but the processing has not been completed. The request might or might not be eventually acted upon, or even maybe disallowed when processing occurs.

Its purpose is to allow a server to accept a request for some other process (perhaps a batch-oriented process that is only run once per day) without requiring that the user agent’s connection to the server persist until the process is completed.

The entity returned with this response SHOULD include an indication of the request’s current status and either a pointer to a status monitor (job queue location) or some estimate of when the user can expect the request to be fulfilled.

204 (No Content)

The 204 status code is usually sent out in response to a PUT, POST, or DELETE request when the REST API declines to send back any status message or representation in the response message’s body.

An API may also send 204 in conjunction with a GET request to indicate that the requested resource exists, but has no state representation to include in the body.

If the client is a user agent, it SHOULD NOT change its document view from that which caused the request to be sent. This response is primarily intended to allow input for actions to take place without causing a change to the user agent’s active document view. However, any new or updated metainformation SHOULD be applied to the document currently in the user agent’s dynamic view.

The 204 response MUST NOT include a message-body and thus is always terminated by the first empty line after the header fields.

301 (Moved Permanently)

The 301 status code indicates that the REST API’s resource model has been significantly redesigned, and a new permanent URI has been assigned to the client’s requested resource. The REST API should specify the new URI in the response’s Location header, and all future requests should be directed to the given URI.

You will hardly use this response code in your API as you can always use the API versioning for the new API while retaining the old one.

302 (Found)

The HTTP response status code 302 Found is a common way of performing URL redirection. An HTTP response with this status code will additionally provide a URL in the Location header field. The user agent (e.g., a web browser) is invited by a response with this code to make a second. Otherwise identical, request to the new URL specified in the location field.

Many web browsers implemented this code in a manner that violated this standard, changing the request type of the new request to GET, regardless of the type employed in the original request (e.g., POST). RFC 1945 and RFC 2068 specify that the client is not allowed to change the method on the redirected request. The status codes 303 and 307 have been added for servers that wish to make unambiguously clear which kind of reaction is expected of the client.

303 (See Other)

A 303 response indicates that a controller resource has finished its work, but instead of sending a potentially unwanted response body, it sends the client the URI of a response resource. The response can be the URI of the temporary status message, or the URI to some already existing, more permanent, resource.

Generally speaking, the 303 status code allows a REST API to send a reference to a resource without forcing the client to download its state. Instead, the client may send a GET request to the value of the Location header.

The 303 response MUST NOT be cached, but the response to the second (redirected) request might be cacheable.

304 (Not Modified)

This status code is similar to 204 (“No Content”) in that the response body must be empty. The critical distinction is that 204 is used when there is nothing to send in the body, whereas 304 is used when the resource has not been modified since the version specified by the request headers If-Modified-Since or If-None-Match.

In such a case, there is no need to retransmit the resource since the client still has a previously-downloaded copy.

Using this saves bandwidth and reprocessing on both the server and client, as only the header data must be sent and received in comparison to the entirety of the page being re-processed by the server, then sent again using more bandwidth of the server and client.

307 (Temporary Redirect)

A 307 response indicates that the REST API is not going to process the client’s request. Instead, the client should resubmit the request to the URI specified by the response message’s Location header. However, future requests should still use the original URI.

A REST API can use this status code to assign a temporary URI to the client’s requested resource. For example, a 307 response can be used to shift a client request over to another host.

The temporary URI SHOULD be given by the Location field in the response. Unless the request method was HEAD, the entity of the response SHOULD contain a short hypertext note with a hyperlink to the new URI(s). If the 307 status code is received in response to a request other than GET or HEAD, the user agent MUST NOT automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which the request was issued.

400 (Bad Request)

400 is the generic client-side error status, used when no other 4xx error code is appropriate. Errors can be like malformed request syntax, invalid request message parameters, or deceptive request routing etc.

The client SHOULD NOT repeat the request without modifications.

401 (Unauthorized)

A 401 error response indicates that the client tried to operate on a protected resource without providing the proper authorization. It may have provided the wrong credentials or none at all. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource.

The client MAY repeat the request with a suitable Authorization header field. If the request already included Authorization credentials, then the 401 response indicates that authorization has been refused for those credentials. If the 401 response contains the same challenge as the prior response, and the user agent has already attempted authentication at least once, then the user SHOULD be presented the entity that was given in the response, since that entity might include relevant diagnostic information.

403 (Forbidden)

A 403 error response indicates that the client’s request is formed correctly, but the REST API refuses to honor it, i.e., the user does not have the necessary permissions for the resource. A 403 response is not a case of insufficient client credentials; that would be 401 (“Unauthorized”).

Authentication will not help, and the request SHOULD NOT be repeated. Unlike a 401 Unauthorized response, authenticating will make no difference.

404 (Not Found)

The 404 error status code indicates that the REST API can’t map the client’s URI to a resource but may be available in the future. Subsequent requests by the client are permissible.

No indication is given of whether the condition is temporary or permanent. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address. This status code is commonly used when the server does not wish to reveal exactly why the request has been refused, or when no other response is applicable.

405 (Method Not Allowed)

The API responds with a 405 error to indicate that the client tried to use an HTTP method that the resource does not allow. For instance, a read-only resource could support only GET and HEAD, while a controller resource might allow GET and POST, but not PUT or DELETE.

A 405 response must include the Allow header, which lists the HTTP methods that the resource supports. For example:

Allow: GET, POST

406 (Not Acceptable)

The 406 error response indicates that the API is not able to generate any of the client’s preferred media types, as indicated by the Accept request header. For example, a client request for data formatted as application/xml will receive a 406 response if the API is only willing to format data as application/json.

If the response could be unacceptable, a user agent SHOULD temporarily stop receipt of more data and query the user for a decision on further actions.

412 (Precondition Failed)

The 412 error response indicates that the client specified one or more preconditions in its request headers, effectively telling the REST API to carry out its request only if certain conditions were met. A 412 response indicates that those conditions were not met, so instead of carrying out the request, the API sends this status code.

415 (Unsupported Media Type)

The 415 error response indicates that the API is not able to process the client’s supplied media type, as indicated by the Content-Type request header. For example, a client request including data formatted as application/xml will receive a 415 response if the API is only willing to process data formatted as application/json.

For example, the client uploads an image as image/svg+xml, but the server requires that images use a different format.

500 (Internal Server Error)

500 is the generic REST API error response. Most web frameworks automatically respond with this response status code whenever they execute some request handler code that raises an exception.

A 500 error is never the client’s fault, and therefore, it is reasonable for the client to retry the same request that triggered this response and hope to get a different response.

The API response is the generic error message, given when an unexpected condition was encountered and no more specific message is suitable.

501 (Not Implemented)

The server either does not recognize the request method, or it cannot fulfill the request. Usually, this implies future availability (e.g., a new feature of a web-service API).

References :

https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml

Содержание

Что такое код ответа HTTP

Как проверить код состояния страницы

В браузере

В Яндекс.Вебмастере

В Google Search Console

1* класс кодов (информационные сообщения)

100 Continue

101 Switching Protocols

102 Processing

103 Checkpoint

105 Name Not Resolved

2* класс кодов (успешно обработанные запросы)

200 ОК

201 Created

202 Accepted

203 Non‑Authoritative Information

204 No Content

205 Reset Content

206 Partial Content

207 Multi‑Status

226 IM Used

3* класс кодов (перенаправление на другой адрес)

300 Multiple Choices

301 Moved Permanently

302 Found/Moved 

303 See Other

304 Not Modified

305 Use Proxy

306 Unused

307 Temporary Redirect

308 Resume Incomplete

4* класс кодов (ошибки на стороне клиента)

400 Bad Request

401 Unauthorized

402 Payment Required

403 Forbidden

404 Not Found

405 Method Not Allowed

406 Not Acceptable

407 Proxy Authentication Required

408 Request Timeout

409 Conflict

410 Gone

411 Length Required

412 Precondition Failed

413 Request Entity Too Large

414 Request‑URI Too Long

415 Unsupported Media Type

416 Requested Range Not Satisfiable

417 Expectation Failed

418 I’m a teapot

422 Unprocessable Entity

423 Locked

424 Failed Dependency

425 Unordered Collection

426 Upgrade Required

428 Precondition Required

429 Too Many Requests

431 Request Header Fields Too Large

434 Requested Host Unavailable

444 No Response

449 Retry With

450 Blocked by Windows Parental Controls

451 Unavailable For Legal Reasons

456 Unrecoverable Error

499 Client Closed Request

5* класс кодов (ошибки на стороне сервера)

500 Internal Server Error

501 Not Implemented

502 Bad Gateway

503 Service Unavailable

504 Gateway Timeout

505 HTTP Version Not Supported

506 Variant Also Negotiates

507 Insufficient Storage

508 Loop Detected

509 Bandwidth Limit Exceeded

510 Not Extended

511 Network Authentication Required

Составили подробный классификатор кодов состояния HTTP. Добавляйте в закладки, чтобы был под рукой, когда понадобится.

Что такое код ответа HTTP

Когда посетитель переходит по ссылке на сайт или вбивает её в поисковую строку вручную, отправляется запрос на сервер. Сервер обрабатывает этот запрос и выдаёт ответ — трехзначный цифровой код HTTP от 100 до 510. По коду ответа можно понять реакцию сервера на запрос. 

Первая цифра в ответе обозначает класс состояния, другие две — причину, по которой мог появиться такой ответ.

Как проверить код состояния страницы

Проверить коды ответа сервера можно вручную с помощью браузера и в панелях веб‑мастеров: Яндекс.Вебмастер и Google Search Console.

В браузере

Для примера возьмём Google Chrome.

1. Откройте панель разработчика в браузере клавишей F12, комбинацией клавиш Ctrl + Shift + I или в меню браузера → «Дополнительные инструменты» → «Инструменты разработчика». Подробнее об этом рассказывали в статье «Как открыть исходный код страницы». 

2. Переключитесь на вкладку «Сеть» в Инструментах разработчика и обновите страницу: 

В Яндекс.Вебмастере

Откройте инструмент «Проверка ответа сервера» в Вебмастере. Введите URL в специальное поле и нажмите кнопку «Проверить»:

Как добавить сайт в Яндекс.Вебмастер и другие сервисы Яндекса

В Google Search Console

Чтобы посмотреть код ответа сервера в GSC, перейдите в инструмент проверки URL — он находится в самом верху панели:

Введите ссылку на страницу, которую хотите проверить, и нажмите Enter. В результатах проверки нажмите на «Изучить просканированную страницу» в блоке «URL есть в индексе Google».

А затем в открывшемся окне перейдите на вкладку «Подробнее»:

Теперь расскажем подробнее про все классы кодов состояния HTTP.

1* класс кодов (информационные сообщения)

Это системный класс кодов, который только информирует о процессе передачи запроса. Такие ответы не являются ошибкой, хотя и могут отображаться в браузере как Error Code.

100 Continue

Этот ответ сообщает, что полученные сведения о запросе устраивают сервер и клиент может продолжать отправлять данные. Такой ответ может требоваться клиенту, если на сервер отправляется большой объём данных.

101 Switching Protocols

Сервер одобрил переключение типа протокола, которое запросил пользователь, и в настоящий момент выполняет действие.

102 Processing

Запрос принят — он находится в обработке, и на это понадобится чуть больше времени.

103 Checkpoint

Контрольная точка — используется в запросах для возобновления после прерывания запросов POST или PUT.

105 Name Not Resolved

Не удается преобразовать DNS‑адрес сервера — это  означает ошибку в службе DNS. Эта служба преобразует IP‑адреса в знакомые нам доменные имена.

2* класс кодов (успешно обработанные запросы)

Эти коды информируют об успешности принятия и обработки запроса. Также сервер может передать заголовки или тело сообщений. 

200 ОК

Все хорошо — HTTP‑запрос успешно обработан (не ошибка).

201 Created

Создано — транзакция успешна, сформирован новый ресурс или документ.

202 Accepted

Принято — запрос принят, но ещё не обработан.

203 Non‑Authoritative Information

Информация не авторитетна — запрос успешно обработан, но передаваемая информация была взята не из первичного источника (данные могут быть устаревшими).

204 No Content

Нет содержимого — запрос успешно обработан, однако в ответе только заголовки без контента сообщения. Не нужно обновлять содержимое документа, но можно применить к нему полученные метаданные.

205 Reset Content

Сбросить содержимое. Запрос успешно обработан — но нужно сбросить введенные данные. Страницу можно не обновлять.

206 Partial Content

Частичное содержимое. Сервер успешно обработал часть GET‑запроса, а другую часть вернул.

При работе с подобными ответами следует уделить внимание кэшированию.

207 Multi‑Status

Успешно выполнено несколько операций — сервер передал результаты выполнения нескольких независимых операций. Они появятся в виде XML‑документа с объектом multistatus. 

226 IM Used

Успешно обработан IM‑заголовок (специальный заголовок, который отправляется клиентом и используется для передачи состояния HTTP).

3* класс кодов (перенаправление на другой адрес)

Эти коды информируют, что для достижения успешной операции нужно будет сделать другой запрос, возможно, по другому URL.

300 Multiple Choices

Множественный выбор — сервер выдает список нескольких возможных вариантов перенаправления (максимум — 5). Можно выбрать один из них.

301 Moved Permanently

Окончательно перемещено — страница перемещена на другой URL, который указан в поле Location.

302 Found/Moved 

Временно перемещено — страница временно перенесена на другой URL,  который указан в поле Location.

303 See Other

Ищите другую страницу — страница не найдена по данному URL, поэтому смотрите страницу по другому URL, используя метод GET.

304 Not Modified

Модификаций не было — с момента последнего визита клиента изменений не было.

305 Use Proxy

Используйте прокси — запрос к нужному ресурсу можно сделать только через прокси‑сервер, URL которого указан в поле Location заголовка.

306 Unused

Зарезервировано. Код в настоящий момент не используется.

307 Temporary Redirect

Временное перенаправление — запрашиваемый ресурс временно доступен по другому URL.

Этот код имеет ту же семантику, что код ответа 302 Found, за исключением того, что агент пользователя не должен изменять используемый метод HTTP: если в первом запросе использовался POST, то во втором запросе также должен использоваться POST.

308 Resume Incomplete

Перемещено полностью (навсегда) — запрашиваемая страница была перенесена на новый URL, указанный в поле Location заголовка. Метод запроса (GET/POST) менять не разрешается.

4* класс кодов (ошибки на стороне клиента)

Эти коды указывают на ошибки со стороны клиентов. 

400 Bad Request

Неверный запрос — запрос клиента не может быть обработан, так как есть синтаксическая ошибка (возможно, опечатка).

401 Unauthorized

Не пройдена авторизация — запрос ещё в обработке, но доступа нет, так как пользователь не авторизован.

Для доступа к запрашиваемому ресурсу клиент должен представиться, послав запрос, включив при этом в заголовок сообщения поле Authorization.

402 Payment Required

Требуется оплата — зарезервировано для использования в будущем. Код предусмотрен для платных пользовательских сервисов, а не для хостинговых компаний.

403 Forbidden

Запрещено — запрос принят, но не будет обработан, так как у клиента недостаточно прав. Может возникнуть, когда пользователь хочет открыть системные файлы (robots, htaccess) или не прошёл авторизацию.

404 Not Found

Не найдено — запрашиваемая страница не обнаружена. Сервер принял запрос, но не нашёл ресурса по указанному URL (возможно, была ошибка в URL или страница была перемещена).

405 Method Not Allowed

Метод не разрешён — запрос был сделан методом, который не поддерживается данным ресурсом. Сервер должен предложить доступные методы решения в заголовке Allow.

406 Not Acceptable

Некорректный запрос — неподдерживаемый поисковиком формат запроса (поисковый робот не поддерживает кодировку или язык).

407 Proxy Authentication Required

Нужно пройти аутентификацию прокси — ответ аналогичен коду 401, только нужно аутентифицировать прокси‑сервер.

408 Request Timeout

Тайм‑аут запроса — запрос клиента занял слишком много времени. На каждом сайте существует свое время тайм‑аута — проверьте интернет‑соединение  и просто обновите страницу.

409 Conflict

Конфликт (что‑то пошло не так) — запрос не может быть выполнен из‑за конфликтного обращения к ресурсу (несовместимость двух запросов).

410 Gone

Недоступно — ресурс раньше был размещён по указанному URL, но сейчас удалён и  недоступен (серверу неизвестно месторасположение).

411 Length Required

Добавьте длины — сервер отклоняет отправляемый запрос, так как длина заголовка не определена, и он не находит значение Content‑Length. 

Нужно исправить заголовки на сервере, и в следующий раз робот сможет проиндексировать страницу.

412 Precondition Failed

Предварительное условие не выполнено — стоит проверить правильность HTTP‑заголовков данного запроса.

413 Request Entity Too Large

Превышен размер запроса — перелимит максимального размера запроса, принимаемого сервером. Браузеры поддерживают запросы от 2 до 8 килобайт.

414 Request‑URI Too Long

Превышена длина запроса — сервер не может обработать запрос из‑за длинного URL. Такая ошибка может возникнуть, например, когда клиент пытается передать чересчур длинные параметры через метод GET, а не POST.

415 Unsupported Media Type

Формат не поддерживается —  сервер не может принять запрос, так как  данные подгружаются в некорректном формате, и сервер разрывает соединение.

416 Requested Range Not Satisfiable

Диапазон не поддерживается — ошибка возникает в случаях, когда в самом HTTP‑заголовке прописывается некорректный байтовый диапазон.

Корректного диапазона в необходимом документе может просто не быть, или есть опечатка в синтаксисе.

417 Expectation Failed

Ожидания не оправдались — прокси некорректно идентифицировал содержимое поля «Expect: 100‑Continue».

418 I’m a teapot

Первоапрельская шутка разработчиков в 1998 году. В расшифровке звучит как «я не приготовлю вам кофе, потому что я чайник». Не используется в работе.

422 Unprocessable Entity

Объект не обработан — сервер принял запрос, но в нём  есть логическая ошибка. Стоит посмотреть в сторону семантики сайта.

423 Locked

Закрыто — ресурс заблокирован для выбранного HTTP‑метода. Можно перезагрузить роутер и компьютер. А также использовать только статистический IP.

424 Failed Dependency

Неуспешная зависимость — сервер не может обработать запрос, так как  один из зависимых ресурсов заблокирован.

Выполнение запроса напрямую зависит от успешности выполнения другой операции, и если она не будет успешно завершена, то вся обработка запроса будет прервана.

425 Unordered Collection

Неверный порядок в коллекции — ошибка возникает, если клиент указал номер элемента в неупорядоченном списке или запросил несколько элементов в порядке, отличном от серверного.

426 Upgrade Required

Нужно обновление — в заголовке ответа нужно корректно сформировать поля Upgrade и Connection. 

Этот ответ возникает, когда серверу требуется обновление до SSL‑протокола, но клиент не имеет его поддержки.

428 Precondition Required

Нужно предварительное условие — сервер просит внести в запрос информацию о предварительных условиях обработки данных, чтобы выдавать корректную информацию по итогу.

429 Too Many Requests

Слишком много запросов — отправлено слишком много запросов за короткое время. Это может указывать, например, на попытку DDoS‑атаки, для защиты от которой запросы блокируются.

431 Request Header Fields Too Large

Превышена длина заголовков — сервер может и не отвечать этим кодом, вместо этого он может просто сбросить соединение.

Исправляется это с помощью сокращения заголовков и повторной отправки запроса.

434 Requested Host Unavailable

Адрес запрашиваемой страницы недоступен.

444 No Response

Нет ответа — код отображается в лог‑файлах, чтобы подтвердить, что сервер никак не отреагировал на запрос пользователя и прервал соединение. Возвращается только сервером nginx.

Nginx — программное обеспечение с открытым исходным кодом. Его используют для создания веб‑серверов, а также  в качестве почтового или обратного прокси‑сервера. Nginx решает проблему падения производительности из‑за роста трафика. 

449 Retry With

Повторите попытку — ошибка говорит о необходимости скорректировать запрос и повторить его снова. Причиной становятся неверно указанные параметры (возможно, недостаточно данных).

450 Blocked by Windows Parental Controls

Заблокировано родительским контролем — говорит о том, что с компьютера попытались зайти на заблокированный ресурс. Избежать этой ошибки можно изменением параметров системы родительского контроля.

451 Unavailable For Legal Reasons

Недоступно по юридическим причинам — доступ к ресурсу закрыт, например, по требованию органов государственной власти или по требованию правообладателя в случае нарушения авторских прав. 

456 Unrecoverable Error

Неустранимая ошибка — при обработке запроса возникла ошибка, которая вызывает некорректируемые сбои в таблицах баз данных.

499 Client Closed Request

Запрос закрыт клиентом — нестандартный код, используемый nginx в ситуациях, когда клиент закрыл соединение, пока nginx обрабатывал запрос.

5* класс кодов (ошибки на стороне сервера)

Эти коды указывают на ошибки со стороны серверов. 

При использовании всех методов, кроме HEAD, сервер должен вернуть в теле сообщения гипертекстовое пояснение для пользователя. И его можно использовать в работе.

500 Internal Server Error

Внутренняя ошибка сервера — сервер столкнулся с неким условием, из‑за которого не может выполнить запрос. 

Проверяйте, корректно ли указаны директивы в системных файлах (особенно htaccess) и нет ли ошибки прав доступа к файлам. Обратите внимание на ошибки внутри скриптов и их медленную работу.

501 Not Implemented

Не выполнено —  код отдается, когда сам сервер не может идентифицировать метод запроса. 

Сами вы эту ошибку не исправите. Устранить её может только сервер.

502 Bad Gateway

Ошибка шлюза — появляется, когда сервер, выступая в роли шлюза или прокси‑сервера, получил ответное сообщение от вышестоящего сервера о несоответствии протоколов.

Актуально исключительно для прокси и шлюзовых конфигураций.

503 Service Unavailable

Временно не доступен — сервер временно не имеет возможности обрабатывать запросы по техническим причинам (обслуживание, перегрузка и прочее). 

В поле Retry‑After заголовка сервер укажет время, через которое  можно повторить запрос.

504 Gateway Timeout

Тайм‑аут шлюза —  сервер, выступая в роли шлюза или прокси‑сервера, не получил ответа от вышестоящего сервера в нужное время.

Исправить эту ошибку самостоятельно не получится. Здесь дело в прокси, часто — в веб‑сервере. 

Первым делом просто обновите веб‑страницу. Если это не помогло, нужно почистить DNS‑кэш. Для этого  нажмите горячие клавиши Windows+R и введите команду cmd (Control+пробел). В открывшемся окне укажите команду ipconfig / flushdns и подтвердите её нажатием Enter.

505 HTTP Version Not Supported

Сервер не поддерживает версию протокола — отсутствует поддержка текущей версии HTTP‑протокола. Нужно обеспечить клиента и сервер одинаковой версией.

506 Variant Also Negotiates

Неуспешные переговоры — с такой ошибкой сталкиваются, если сервер изначально настроен неправильно. По причине ошибочной конфигурации выбранный вариант указывает сам на себя, из‑за чего процесс и прерывается.

507 Insufficient Storage

Не хватает места для хранения — серверу недостаточно места в хранилище. Нужно либо расчистить место, либо увеличить доступное пространство.

508 Loop Detected

Обнаружен цикл — ошибка означает провал запроса и выполняемой операции в целом.

509 Bandwidth Limit Exceeded

Превышена пропускная способность —  используется при чрезмерном потреблении трафика. Владельцу площадки следует обратиться к своему хостинг‑провайдеру. 

510 Not Extended

Не продлён — ошибка говорит, что на сервере отсутствует нужное для клиента расширение. Чтобы исправить проблему, надо убрать часть неподдерживаемого расширения из запроса или добавить поддержку на сервер.

511 Network Authentication Required

Требуется аутентификация — ошибка генерируется сервером‑посредником, к примеру, сервером интернет‑провайдера, если нужно ввести пароль для получения доступа к сети через платную точку доступа.