Asp net core 500 internal server error

User-1158769213 posted

Hello,

I’m just starting with ASP.NET Core, and tried to deploy one today. I was faced with the above error when I tried to load it.

I started VS2017, created a new MVC Core site, and published. I didn’t change a thing, just published the site as it came out of the box.

I then copied the contents of the binReleasenetcoreapp2.2publish folder to my hosting company via FTP, and tried to load the site in a browser.

The hosting company installed Core 2.2 on the server. Do they need to do anything else? I only have control panel access (via SolidCP) to the server, not remote access, so there’s only so much I can do.

If I look in my control panel for the site, I see the following warning…

The web.config file it mentions looks like this…

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <location path="." inheritInChildApplications="false">
    <system.webServer>
      <handlers>
        <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
      </handlers>
      <aspNetCore processPath="dotnet" arguments=".BasicCoreSite.dll" stdoutLogEnabled="false" stdoutLogFile=".logsstdout" hostingModel="InProcess" />
    </system.webServer>
  </location>
</configuration>
<!--ProjectGuid: 2fbe438c-a8b2-4b5b-8224-eb5dfcb62107-->

I tried changing the value of stdoutLogEnabled to «true» to see if that would give me a log file, but I couldn’t see anything appear.

Anyone any idea what went wrong? The hosting company don’t know much about Core, so can’t help.

Thanks for any help you can give.

Handle errors in ASP.NET Core web APIs

This article describes how to handle errors and customize error handling with ASP.NET Core web APIs.

Developer Exception Page

The Developer Exception Page shows detailed stack traces for server errors. It uses DeveloperExceptionPageMiddleware to capture synchronous and asynchronous exceptions from the HTTP pipeline and to generate error responses. For example, consider the following controller action, which throws an exception:

When the Developer Exception Page detects an unhandled exception, it generates a default plain-text response similar to the following example:

If the client requests an HTML-formatted response, the Developer Exception Page generates a response similar to the following example:

To request an HTML-formatted response, set the Accept HTTP request header to text/html .

Don’t enable the Developer Exception Page unless the app is running in the Development environment. Don’t share detailed exception information publicly when the app runs in production. For more information on configuring environments, see Use multiple environments in ASP.NET Core.

Exception handler

In non-development environments, use Exception Handling Middleware to produce an error payload:

In Program.cs , call UseExceptionHandler to add the Exception Handling Middleware:

Configure a controller action to respond to the /error route:

The preceding HandleError action sends an RFC 7807-compliant payload to the client.

Don’t mark the error handler action method with HTTP method attributes, such as HttpGet . Explicit verbs prevent some requests from reaching the action method.

For web APIs that use Swagger / OpenAPI, mark the error handler action with the [ApiExplorerSettings] attribute and set its IgnoreApi property to true . This attribute configuration excludes the error handler action from the app’s OpenAPI specification:

Allow anonymous access to the method if unauthenticated users should see the error.

Exception Handling Middleware can also be used in the Development environment to produce a consistent payload format across all environments:

In Program.cs , register environment-specific Exception Handling Middleware instances:

In the preceding code, the middleware is registered with:

• A route of /error-development in the Development environment.
• A route of /error in non-Development environments.

Add controller actions for both the Development and non-Development routes:

Use exceptions to modify the response

The contents of the response can be modified from outside of the controller using a custom exception and an action filter:

Create a well-known exception type named HttpResponseException :

Create an action filter named HttpResponseExceptionFilter :

The preceding filter specifies an Order of the maximum integer value minus 10. This Order allows other filters to run at the end of the pipeline.

In Program.cs , add the action filter to the filters collection:

Validation failure error response

For web API controllers, MVC responds with a ValidationProblemDetails response type when model validation fails. MVC uses the results of InvalidModelStateResponseFactory to construct the error response for a validation failure. The following example replaces the default factory with an implementation that also supports formatting responses as XML, in Program.cs :

Client error response

An error result is defined as a result with an HTTP status code of 400 or higher. For web API controllers, MVC transforms an error result to produce a ProblemDetails.

The automatic creation of a ProblemDetails for error status codes is enabled by default, but error responses can be configured in one of the following ways:

Default problem details response

The following Program.cs file was generated by the web application templates for API controllers:

Consider the following controller, which returns BadRequest when the input is invalid:

A problem details response is generated with the previous code when any of the following conditions apply:

• The /api/values2/divide endpoint is called with a zero denominator.
• The /api/values2/squareroot endpoint is called with a radicand less than zero.

The default problem details response body has the following type , title , and status values:

Problem details service

ASP.NET Core supports creating Problem Details for HTTP APIs using the IProblemDetailsService. For more information, see the Problem details service.

The following code configures the app to generate a problem details response for all HTTP client and server error responses that don’t have a body content yet:

Consider the API controller from the previous section, which returns BadRequest when the input is invalid:

A problem details response is generated with the previous code when any of the following conditions apply:

• An invalid input is supplied.
• The URI has no matching endpoint.
• An unhandled exception occurs.

The automatic creation of a ProblemDetails for error status codes is disabled when the SuppressMapClientErrors property is set to true :

Using the preceding code, when an API controller returns BadRequest , an HTTP 400 response status is returned with no response body. SuppressMapClientErrors prevents a ProblemDetails response from being created, even when calling WriteAsync for an API Controller endpoint. WriteAsync is explained later in this article.

The next section shows how to customize the problem details response body, using CustomizeProblemDetails, to return a more helpful response. For more customization options, see Customizing problem details.

Customize problem details with CustomizeProblemDetails

The updated API controller:

The following code contains the MathErrorFeature and MathErrorType , which are used with the preceding sample:

A problem details response is generated with the previous code when any of the following conditions apply:

• The /divide endpoint is called with a zero denominator.
• The /squareroot endpoint is called with a radicand less than zero.
• The URI has no matching endpoint.

The problem details response body contains the following when either squareroot endpoint is called with a radicand less than zero:

Implement ProblemDetailsFactory

To customize the problem details response, register a custom implementation of ProblemDetailsFactory in Program.cs :

Use ApiBehaviorOptions.ClientErrorMapping

Use the ClientErrorMapping property to configure the contents of the ProblemDetails response. For example, the following code in Program.cs updates the Link property for 404 responses:

Additional resources

This article describes how to handle errors and customize error handling with ASP.NET Core web APIs.

Developer Exception Page

The Developer Exception Page shows detailed stack traces for server errors. It uses DeveloperExceptionPageMiddleware to capture synchronous and asynchronous exceptions from the HTTP pipeline and to generate error responses. For example, consider the following controller action, which throws an exception:

When the Developer Exception Page detects an unhandled exception, it generates a default plain-text response similar to the following example:

If the client requests an HTML-formatted response, the Developer Exception Page generates a response similar to the following example:

To request an HTML-formatted response, set the Accept HTTP request header to text/html .

Don’t enable the Developer Exception Page unless the app is running in the Development environment. Don’t share detailed exception information publicly when the app runs in production. For more information on configuring environments, see Use multiple environments in ASP.NET Core.

Exception handler

In non-development environments, use Exception Handling Middleware to produce an error payload:

In Program.cs , call UseExceptionHandler to add the Exception Handling Middleware:

Configure a controller action to respond to the /error route:

The preceding HandleError action sends an RFC 7807-compliant payload to the client.

Don’t mark the error handler action method with HTTP method attributes, such as HttpGet . Explicit verbs prevent some requests from reaching the action method.

For web APIs that use Swagger / OpenAPI, mark the error handler action with the [ApiExplorerSettings] attribute and set its IgnoreApi property to true . This attribute configuration excludes the error handler action from the app’s OpenAPI specification:

Allow anonymous access to the method if unauthenticated users should see the error.

Exception Handling Middleware can also be used in the Development environment to produce a consistent payload format across all environments:

In Program.cs , register environment-specific Exception Handling Middleware instances:

In the preceding code, the middleware is registered with:

• A route of /error-development in the Development environment.
• A route of /error in non-Development environments.

Add controller actions for both the Development and non-Development routes:

Use exceptions to modify the response

The contents of the response can be modified from outside of the controller using a custom exception and an action filter:

Create a well-known exception type named HttpResponseException :

Create an action filter named HttpResponseExceptionFilter :

The preceding filter specifies an Order of the maximum integer value minus 10. This Order allows other filters to run at the end of the pipeline.

In Program.cs , add the action filter to the filters collection:

Validation failure error response

For web API controllers, MVC responds with a ValidationProblemDetails response type when model validation fails. MVC uses the results of InvalidModelStateResponseFactory to construct the error response for a validation failure. The following example replaces the default factory with an implementation that also supports formatting responses as XML, in Program.cs :

Client error response

An error result is defined as a result with an HTTP status code of 400 or higher. For web API controllers, MVC transforms an error result to produce a ProblemDetails.

The error response can be configured in one of the following ways:

Implement ProblemDetailsFactory

To customize the problem details response, register a custom implementation of ProblemDetailsFactory in Program.cs :

Use ApiBehaviorOptions.ClientErrorMapping

Use the ClientErrorMapping property to configure the contents of the ProblemDetails response. For example, the following code in Program.cs updates the Link property for 404 responses:

Custom Middleware to handle exceptions

The defaults in the exception handling middleware work well for most apps. For apps that require specialized exception handling, consider customizing the exception handling middleware.

Produce a ProblemDetails payload for exceptions

ASP.NET Core doesn’t produce a standardized error payload when an unhandled exception occurs. For scenarios where it’s desirable to return a standardized ProblemDetails response to the client, the ProblemDetails middleware can be used to map exceptions and 404 responses to a ProblemDetails payload. The exception handling middleware can also be used to return a ProblemDetails payload for unhandled exceptions.

Additional resources

This article describes how to handle and customize error handling with ASP.NET Core web APIs.

Developer Exception Page

The Developer Exception Page is a useful tool to get detailed stack traces for server errors. It uses DeveloperExceptionPageMiddleware to capture synchronous and asynchronous exceptions from the HTTP pipeline and to generate error responses. To illustrate, consider the following controller action:

Run the following curl command to test the preceding action:

The Developer Exception Page displays a plain-text response if the client doesn’t request HTML-formatted output. The following output appears:

To display an HTML-formatted response instead, set the Accept HTTP request header to the text/html media type. For example:

Consider the following excerpt from the HTTP response:

The HTML-formatted response becomes useful when testing via tools like Postman. The following screen capture shows both the plain-text and the HTML-formatted responses in Postman:

Enable the Developer Exception Page only when the app is running in the Development environment. Don’t share detailed exception information publicly when the app runs in production. For more information on configuring environments, see Use multiple environments in ASP.NET Core.

Don’t mark the error handler action method with HTTP method attributes, such as HttpGet . Explicit verbs prevent some requests from reaching the action method. Allow anonymous access to the method if unauthenticated users should see the error.

Exception handler

In non-development environments, Exception Handling Middleware can be used to produce an error payload:

In Startup.Configure , invoke UseExceptionHandler to use the middleware:

Configure a controller action to respond to the /error route:

The preceding Error action sends an RFC 7807-compliant payload to the client.

Exception Handling Middleware can also provide more detailed content-negotiated output in the local development environment. Use the following steps to produce a consistent payload format across development and production environments:

In Startup.Configure , register environment-specific Exception Handling Middleware instances:

In the preceding code, the middleware is registered with:

• A route of /error-local-development in the Development environment.
• A route of /error in environments that aren’t Development.

Apply attribute routing to controller actions:

The preceding code calls ControllerBase.Problem to create a ProblemDetails response.

Use exceptions to modify the response

The contents of the response can be modified from outside of the controller. In ASP.NET 4.x Web API, one way to do this was using the HttpResponseException type. ASP.NET Core doesn’t include an equivalent type. Support for HttpResponseException can be added with the following steps:

Create a well-known exception type named HttpResponseException :

Create an action filter named HttpResponseExceptionFilter :

The preceding filter specifies an Order of the maximum integer value minus 10. This Order allows other filters to run at the end of the pipeline.

In Startup.ConfigureServices , add the action filter to the filters collection:

Validation failure error response

For web API controllers, MVC responds with a ValidationProblemDetails response type when model validation fails. MVC uses the results of InvalidModelStateResponseFactory to construct the error response for a validation failure. The following example uses the factory to change the default response type to SerializableError in Startup.ConfigureServices :

Client error response

An error result is defined as a result with an HTTP status code of 400 or higher. For web API controllers, MVC transforms an error result to a result with ProblemDetails.

The error response can be configured in one of the following ways:

Implement ProblemDetailsFactory

To customize the problem details response, register a custom implementation of ProblemDetailsFactory in Startup.ConfigureServices :

Use ApiBehaviorOptions.ClientErrorMapping

Use the ClientErrorMapping property to configure the contents of the ProblemDetails response. For example, the following code in Startup.ConfigureServices updates the type property for 404 responses:

Custom Middleware to handle exceptions

The defaults in the exception handling middleware work well for most apps. For apps that require specialized exception handling, consider customizing the exception handling middleware.

Источник

I did include the output of dotnet --into output in my original report.

The full stack trace is:

System.InvalidOperationException: The instance of entity type 'TodoItem' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the conflicting key values.
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.IdentityMap`1.ThrowIdentityConflict(InternalEntityEntry entry)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.IdentityMap`1.Add(TKey key, InternalEntityEntry entry, Boolean updateDuplicate)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.StartTracking(InternalEntityEntry entry)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetEntityState(EntityState oldState, EntityState newState, Boolean acceptChanges)
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetEntityState(EntityState entityState, Boolean acceptChanges, Nullable`1 forceStateWhenUnknownKey)
   at Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry.set_State(EntityState value)
   at TodoApi.Controllers.TodoController.PutTodoItem(Int64 id, TodoItem todoItem) in /home/sjm/tmp/Docs/aspnetcore/tutorials/first-web-api/samples/2.2/TodoApi/Controllers/TodoController.cs:line 80
   at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

The line that causes the exception is:

_context.Entry(todoItem).State = EntityState.Modified;

If I use a different ID in either the URL or payload I get:

{
    "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
    "title": "Bad Request",
    "status": 400,
    "traceId": "0HLK5A8VJ9L24:00000001"
}

I’ve found something strange: it only fails if it’s the first request. It seems if I make any other request first (even one that fails), then the PUT works.