Syntax error unexpected token in json at position 0 opencart

27.05.2020 0 Автор: John Просмотров: 4299

SyntaxError: Unexpected token < in JSON at position 0

Introduction

A common issue that I see when working with front-end JavaScript heavy apps is the dreaded “SyntaxError Unexpected Token in JSON” error! Now this error can be of the form:

SyntaxError: Unexpected token < in JSON at position 0

SyntaxError: Unexpected end of JSON input

syntaxerror: unexpected token '<', "<!doctype "... is not valid json

The error “SyntaxError Unexpected Token in JSON” appears when you try to parse content (for example — data from a database, api, etc), but the content itself is not JSON (could be XML, HTML, CSV) or invalid JSON containing unescaped characters, missing commas and brackets.

There are a few things you can try to fix this error:

1. Check that the content you are trying to parse is JSON format and not HTML or XML

2. Verify that there are no missing or extra commas.

3. Make sure to check for unescaped special characters.

4. Check for mismatched brackets or quotes.

5. Make sure the JSON is valid. You can use a tool like JSONLint to validate your JSON and check for any errors.

1. Check that the content you are trying to parse is JSON format and not HTML or XML

A common reason why the error “SyntaxError Unexpected Token in JSON” comes up is that we are trying to parse content that is not even JSON.

Consider the following front-end JavaScript code:

  

fetch('https://localhost:3000/data')
  .then(response => response.json())
  .then(data => {
    console.log(data);
    // Use the data here
  })

In the above example, the fetch() function is being used to retrieve data from a API that returns JSON format — in this case https://localhost:3000/data.

The fetch() function then returns a promise, and when that promise resolves, we handle that with the response.json() method. This just takes our JSON response and converts it to a JSON object to be used!

After that we just console.log out the data object

Now for the server-side of things, look on to our Node JS route that returns the JSON /data

  

var http = require('http');

var app = http.createServer(function(req,res){
    res.setHeader('Content-Type', 'text/html'); ❌ Not returning JSON.
    res.end(JSON.stringify({ a: 1 }));
});
app.listen(3000);

We can see that it is setting the Header as text/html. This will give you the error:

syntaxerror: unexpected token '<', "<!doctype "... is not valid json

This is because we are trying to parse the content with JSON.parse() or in our case response.json() and receiving a HTML file!

To fix this, we just need to change the returned header to res.setHeader('Content-Type', 'application/json'):

  

...
var app = http.createServer(function(req,res){
    res.setHeader('Content-Type', 'application/json'); ✔️ Returning JSON.
    res.end(JSON.stringify({ a: 1 }));
});
...

Whats Content-Type request header anyway?

Pretty much every resource on the internet will need to have a type (similar to how your file system contains file types like images, videos, text, etc).
This is known as a MIME type (Multipurpose Internet Mail Extension)

Browsers need to know what content type a resource is so that it can best handle it. Most modern browsers are becoming good at figuring out which content type a resource is, but its not always 100% correct.

That is why still need to explicitly specify our request header content-type!

syntaxerror: unexpected token ‘<’, “<!doctype “… is not valid json

This error also comes up when your API is returning invalid error pages such as 404/500 HTML pages. Since HTML usually starts with a “less than” tag symbol (<) and JSON is not valid with < tags, it will through this error.

For example, when everything is working find, your node API will happily return JSON. However when it fails with a 500 internal error, it could return a custom HTML error page!
In this case, when you try to do JSON.parse(data) you will get the syntaxerror: unexpected token '<', "<!doctype "... is not valid json.

Additionally, check that you are calling the correct API url. As an example, lets say the API that returns JSON is using the /data route. If you misspelt this, you could be redirected to a 404 HTML page instead!

Tip: Use appropriate error handlers for non-JSON data

If you are using fetch() to retrieve your data, we can add a catch handler to give meaningful error messages to the user:

  

fetch('https://localhost:3000/data')
  .then(response => response.json())
  .then(data => {
    console.log(data);
    // Use the data here
  })
  .catch(error => console.error(error)); /*✔️ Friendly error message for debugging! */

If you are using JSON.parse() we can do this in a try/catch block as follows:

  

try {
    JSON.parse(data);
}
catch (error) {
    console.log('Error parsing JSON:', error, data); /*✔️ Friendly message for debugging ! */
}

JSON objects and arrays should have a comma between each item, except for the last one.

  

{
    "name": "John Smith"
    "age": 30
    "address": {
        "street": "123 Main St"
        "city": "Anytown"
        "state": "USA"
    }
}

This JSON object will throw a “syntaxerror unexpected token” error because there is no comma between “John Smith” and “age”, and also between “Anytown” and “state”.

To fix this, you would add commas as follows:

  

{
    "name": "John Smith",
    "age": 30,
    "address": {
        "street": "123 Main St",
        "city": "Anytown",
        "state": "USA"
    }
}

By adding commas between each item except for the last one, the JSON object is now in the correct format and should parse without error.

3. Make sure to use double quotes and escape special characters.

JSON strings must be wrapped in double quotes, and any special characters within the string must be properly escaped. Consider the following example:

  

{
    "name": "John Smith",
    "age": 30,
    "address": {
        "street": "123 Main St",
        "city": "Anytown",
        "state": "USA"
    },
    "message": "It's a lovely day"
}

When we try to parse this with JSON.parse, we will get the error: SyntaxError: Invalid or unexpected token.

The problem is with the following line using a apostrophe:

"message": "It's a lovely day"

  

{
    "name": "John Smith",
    "age": 30,
    "address": {
        "street": "123 Main St",
        "city": "Anytown",
        "state": "USA"
    },
    "message": "It's a lovely day"
}

As we can see, this will fix our error since we escape the aspostrophe as such:

"message": "It's a lovely day"

4. Check for mismatched brackets or quotes.

Make sure all brackets and quotes are properly closed and match up.

  

{
    "name": "John Smith",
    "age": 30,
    "address": {
        "street": "123 Main St",
        "city": "Anytown",
        "state": "USA"
    }

In this example, the JSON object is missing a closing curly bracket, which indicates the end of the object. Because of this, it will throw a “syntaxerror unexpected token” error.

To fix this, you would add the missing closing curly bracket as follows:

  

{
    "name": "John Smith",
    "age": 30,
    "address": {
        "street": "123 Main St",
        "city": "Anytown",
        "state": "USA"
    }
}

If you want to be sure that the JSON is valid, we can try to use the NPM package JSONLint (https://github.com/zaach/jsonlint)

We can install jsonlint with npm as follows:

1. Open up the terminal
2. Run NPM install npm install jsonlint -g
3. We can then validate a file like so: jsonlint myfile.json

Summary

In this article I went over the SyntaxError: Unexpected token < in JSON at position 0 when dealing with parsing JSON with fetch or JSON.parse. This error is mainly due to the JSON not being in correct format or the content that we are trying to parse is not even JSON.

In the case of JSON being invalid, make sure to check for unescaped characters, missing commas, non-matching brackets and quotes.

To be really sure, check the JSON with tools like JSONLint to validate!

In the case of the content you are trying to parse being non-JSON such as HTML, check your API to make sure that error pages return JSON correctly instead of HTML pages.

Syntax Error: Unexpected token OpenCart Community Forum

Syntax Error: Unexpected token

Post by matchamr » Mon Jun 06, 2016 4:46 pm

Can anyone help with an issue I have when going to edit an order as an opencart administrator.

I get an error message titled ‘Syntax Error: Unexpected token

Re: Syntax Error: Unexpected token

Post by i2Paq » Mon Jun 06, 2016 4:51 pm

This error appears quite often in other installs.

Have you used our FREE search on: JSON at position 0.

Norman in ‘t Veldt
Moderator OpenCart Forums
_________________ READ and Search BEFORE POSTING _________________

Our FREE search: Find your answer FAST!.

Re: Syntax Error: Unexpected token

Post by artcore » Mon Jun 06, 2016 6:04 pm

Attn: I no longer provide OpenCart extensions, nor future support — this includes forum posts.
Reason: OpenCart version 3+

Re: Syntax Error: Unexpected token

Post by i2Paq » Mon Jun 06, 2016 6:11 pm

Could you explain what this does?

In my .htaccess I have this:

Norman in ‘t Veldt
Moderator OpenCart Forums
_________________ READ and Search BEFORE POSTING _________________

Our FREE search: Find your answer FAST!.

Re: Syntax Error: Unexpected token

Post by artcore » Mon Jun 06, 2016 7:28 pm

Attn: I no longer provide OpenCart extensions, nor future support — this includes forum posts.
Reason: OpenCart version 3+

Re: Syntax Error: Unexpected token

Post by matchamr » Tue Jun 07, 2016 3:27 am

Thank you kindly for taking the time to assist. I have copied both of your codes into my htaccess file, however the same result occurs. My entire htaccess file in the root directory reads (I’ve also tried the other suggestion): (note I am using journal2 them — will this make a difference?) Any suggestions? Thank you.

htaccess:
AddType x-httpd-php54 .php

Re: Syntax Error: Unexpected token

Post by artcore » Tue Jun 07, 2016 4:23 am

If that is the only content in your htaccess, you should get a fresh copy from the opencart download section first and optionally add the addition.

To solve your issue, try this:

Go to Admin > Settings > Users > API
Create a new API and enable it
Next, go to Store Settings
Under Option tab in the Checkout section > API user > select
Save

Attn: I no longer provide OpenCart extensions, nor future support — this includes forum posts.
Reason: OpenCart version 3+

Источник

[SOLVED] — Syntax error: Unexpected token OpenCart Community Forum

[SOLVED] — Syntax error: Unexpected token

Post by blongso » Sun May 03, 2020 3:42 am

Re: Syntax error: Unexpected token

Post by straightlight » Sun May 03, 2020 4:15 am

Dedication and passion goes to those who are able to push and merge a project.

Regards,
Straightlight
Programmer / Opencart Tester

Re: Syntax error: Unexpected token

Post by IP_CAM » Sun May 03, 2020 4:54 am

My Github OC Site: https://github.com/IP-CAM
5’000 + FREE OC Extensions, on the World’s largest Github OC Repository Archive Site.

Re: Syntax error: Unexpected token

Post by blongso » Sun May 03, 2020 5:21 am

Re: [SOLVED] — Syntax error: Unexpected token

Post by IP_CAM » Sun May 03, 2020 6:53 am

My Github OC Site: https://github.com/IP-CAM
5’000 + FREE OC Extensions, on the World’s largest Github OC Repository Archive Site.

Re: [SOLVED] — Syntax error: Unexpected token

Post by letxobnav » Sun May 03, 2020 12:19 pm

“Data security is paramount at [. ], and we are committed to protecting the privacy of anyone who is associated with our [. ]. We’ve made a lot of improvements and will continue to make them.”
When you know your life savings are gone.

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syntaxError: unexpected token

Post by Ramsdej » Sun May 17, 2020 11:32 pm

I hope someone can help.

I get the error

This happens when I try to install any extensions. I am using the latest version of Opencart, with a clean install.

Thank you all in advance.

Re: syntaxError: unexpected token

Post by straightlight » Sun May 17, 2020 11:53 pm

Dedication and passion goes to those who are able to push and merge a project.

Regards,
Straightlight
Programmer / Opencart Tester

Re: syntaxError: unexpected token

Post by Ramsdej » Mon May 18, 2020 12:37 am

Thanks for the reply, Im using the latest versions of Opencart. I have followed your suggestion to the latter and I am still getting the same error when trying to install a module.

Re: syntaxError: unexpected token

Post by straightlight » Mon May 18, 2020 12:42 am

Dedication and passion goes to those who are able to push and merge a project.

Regards,
Straightlight
Programmer / Opencart Tester

Re: syntaxError: unexpected token

Post by Ramsdej » Mon May 18, 2020 12:48 am

I have replaced the installer.php file with the one you suggested.

I am getting these errors now.

Re: syntaxError: unexpected token

Post by straightlight » Mon May 18, 2020 12:53 am

Those errors are definitely related to permission issues. If you did followed install.txt file’s instructions to the letter but still encounter folder permissions after switching those permissions recursively from your FTP and this problem persists afterwards, the quickest way to resolved this would be by contacting your host.

As a second option, you could also create a new service request in the Commercial Support section of the forum, or contact a reliable Opencart partner from the Resources menu link on the top of the site, or contact me directly via PM to solved this issue as a custom job.

Dedication and passion goes to those who are able to push and merge a project.

Regards,
Straightlight
Programmer / Opencart Tester

Источник

syntax error unexpected token in json at position 0, permission denied! when Edit Order

syntax error unexpected token in json at position 0, permission denied! when Edit Order

Post by sansou » Wed Jul 17, 2019 10:37 pm

Re: syntax error unexpected token in json at position 0, permission denied! when Edit Order

Post by paulfeakins » Thu Jul 18, 2019 5:49 pm

Re: syntax error unexpected token in json at position 0, permission denied! when Edit Order

Post by sansou » Sat Jul 20, 2019 4:43 pm

Re: syntax error unexpected token in json at position 0, permission denied! when Edit Order

Post by sansou » Sat Jul 20, 2019 5:05 pm

Re: syntax error unexpected token in json at position 0, permission denied! when Edit Order

Post by paulfeakins » Sun Jul 21, 2019 5:36 pm

Re: syntax error unexpected token in json at position 0, permission denied! when Edit Order

Post by sansou » Sat Aug 10, 2019 6:38 pm

Re: syntax error unexpected token in json at position 0, permission denied! when Edit Order

Post by paulfeakins » Mon Aug 12, 2019 5:46 pm

Re: syntax error unexpected token in json at position 0, permission denied! when Edit Order

Post by letxobnav » Mon Aug 12, 2019 6:21 pm

“Data security is paramount at [. ], and we are committed to protecting the privacy of anyone who is associated with our [. ]. We’ve made a lot of improvements and will continue to make them.”
When you know your life savings are gone.

Источник

Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by dragos_mihai » Sat Sep 19, 2020 1:26 am

Hi, i have this problem every time I enter from the admin page into clients order (only here it appears). The worst thing is that i can’t update the order status because this error appears: Syntax Error: Unexpected token in JSON at position 0 error
Opencart version is 2.2.0.0

Please help me, i have 3 month trying to fix it without succes.
I attached ss with the entire error.

Attachments

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Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by OSWorX » Sat Sep 19, 2020 11:16 am

Full Stack Web Developer :: Dedicated OpenCart Development & Support DACH Region
Contact for Custom Work / Fast Support.

Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by thekrotek » Sat Sep 19, 2020 3:15 pm

Professional OpenCart extensions, support and custom work.
Contact me via email or Skype by support@thekrotek.com

Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by OSWorX » Sun Sep 20, 2020 1:27 am

Full Stack Web Developer :: Dedicated OpenCart Development & Support DACH Region
Contact for Custom Work / Fast Support.

Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by dragos_mihai » Sun Sep 20, 2020 3:48 am

I didn’t because this problem appeared after i changed into https. Until then everything was good

I checked the error log but it’s empty

Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by thekrotek » Sun Sep 20, 2020 4:12 am

Professional OpenCart extensions, support and custom work.
Contact me via email or Skype by support@thekrotek.com

Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by OSWorX » Sun Sep 20, 2020 4:22 am

Full Stack Web Developer :: Dedicated OpenCart Development & Support DACH Region
Contact for Custom Work / Fast Support.

Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by dragos_mihai » Sun Sep 20, 2020 4:26 am

Attachments

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Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by dragos_mihai » Sun Sep 20, 2020 4:30 am

Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by OSWorX » Sun Sep 20, 2020 4:31 am

Full Stack Web Developer :: Dedicated OpenCart Development & Support DACH Region
Contact for Custom Work / Fast Support.

Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by dragos_mihai » Sun Sep 20, 2020 6:04 am

Attachments

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Re: Syntax Error: Unexpected token in JSON at position 0 error (admin page)

Post by OSWorX » Sun Sep 20, 2020 6:28 am

First, you wrote that you have changed to https.
These days a website without https is nothing, a webshop useless — therefore late but done now.

Second: did you try it also with that:

Third: you wrote in your first post:

That means, a call via ajax is made to frontend controller by the API.
Have you checked also if the admin API is set correct?

And finally — as already written — some of the extensions (standard) shipping or payments had some bugs in 2.2.0.0
Which paymetn and shipping are assingned to these orders?

Last: before this here is growing to a «never ending story», either you can fix that by yourself, or hire a developer.
A OpenCart Professional can fix that within 5 minutes.

Full Stack Web Developer :: Dedicated OpenCart Development & Support DACH Region
Contact for Custom Work / Fast Support.

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