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Chrome refuses to execute an AJAX script due to wrong MIME type


Question

I'm trying to access a script as JSON via AJAX, which works fine on Safari and other browsers but unfortunately will not execute in Chrome. It's coming with the following error:

Refused to execute script from '*' because its MIME type ('application/json') is not executable, and strict MIME type checking is enabled.

Here's the request:

$.ajax({
    url: "http://some_url/test.json?callback=?",
    type: "GET",
    dataType: 'json',
    cache: true,
    success: function (data, status, error) {
      console.log('success', data);
    },
    error: function (data, status, error) {
      console.log('error', data, status, error);
    }
});

Does anyone have a workaround for this?

2017/05/04
1
146
5/4/2017 3:21:34 PM

Accepted Answer

By adding a callback argument, you are telling jQuery that you want to make a request for JSONP using a script element instead of a request for JSON using XMLHttpRequest.

JSONP is not JSON. It is a JavaScript program.

Change your server so it outputs the right MIME type for JSONP which is application/javascript.

(While you are at it, stop telling jQuery that you are expecting JSON as that is contradictory: dataType: 'jsonp').

2014/07/02
71
7/2/2014 10:17:48 AM

If your proxy server or container adds the following header when serving the .js file, it will force some browsers such as Chrome to perform strict checking of MIME types:

X-Content-Type-Options: nosniff

Remove this header to prevent Chrome performing the MIME check.

2014/12/03

FYI, I've got the same error from Chrome console. I thought my AJAX function causing it, but I uncommented my minified script from /javascripts/ajax-vanilla.min.js to /javascripts/ajax-vanilla.js. But in reality the source file was at /javascripts/src/ajax-vanilla.js. So in Chrome you getting bad MIME type error even if the file cannot be found. In this case, the error message is described as text/plain bad MIME type.

2017/07/17

For the record and Google search users, If you are a .NET Core developer, you should set the content-types manually, because their default value is null or empty:

var provider = new FileExtensionContentTypeProvider();
app.UseStaticFiles(new StaticFileOptions
{
    ContentTypeProvider = provider
});
2018/03/13

I encountered this error using IIS 7.0 with a custom 404 error page, although I suspect this will happen with any 404 page. The server returned an html 404 response with a text/html mime type which could not (rightly) be executed.

2016/05/24

In my case, I use

$.getJSON(url, function(json) { ... });

to make the request (to Flickr's API), and I got the same MIME error. Like the answer above suggested, adding the following code:

$.ajaxSetup({ dataType: "jsonp" });

Fixed the issue and I no longer see the MIME type error in Chrome's console.

2015/03/20