Missing .map resource?

I've recently started having this problem with all my projects. When my index page loads which contains a reference to the jquery source file, my console logs this error: GET http://localhost:3000/js/lib/jquery-1.10.2.min.map 500 (Internal Server Error).

This doesn't affect my application at all, but it's really annoying to see whenever I open up the console. Does anyone know where this is coming from?

Edit: Note that I'm not explicitly referencing the .map file, I am just pointing to <script src="js/lib/jquery-1.10.2.min.js"></script>

jQuery recently started using source maps.

For example, let's look at the minified jQuery 2.0.3 file's first few lines.

/*! jQuery v2.0.3 | (c) 2005, 2013 jQuery Foundation, Inc. | jquery.org/license
//@ sourceMappingURL=jquery.min.map
*/

Excerpt from Introduction to JavaScript Source Maps:

> Have you ever found yourself wishing you could keep your client-side > code readable and more importantly debuggable even after you've > combined and minified it, without impacting performance? Well now you > can through the magic of source maps. > > Basically it's a way to map a combined/minified file back to an > unbuilt state. When you build for production, along with minifying and > combining your JavaScript files, you generate a source map which holds > information about your original files. When you query a certain line > and column number in your generated JavaScript you can do a lookup in > the source map which returns the original location. Developer tools > (currently WebKit nightly builds, Google Chrome, or Firefox 23+) can > parse the source map automatically and make it appear as though you're > running unminified and uncombined files.

^{emphasis mine}

It's incredibly useful, and will only download if the user opens dev tools.

Solution

Remove the source mapping line, or do nothing. It isn't really a problem.

---

Side note: your server should return 404, not 500. It could point to a security problem if this happens in production.

I had similar expirience like yours. I have Denwer server. When I loaded my http://new.new local site without using via script src jquery.min.js file at index.php in Chrome I got error 500 jquery.min.map in console. I resolved this problem simply - I disabled extension Wunderlist in Chrome and voila - I never see this error more. Although, No, I found this error again - when Wunderlist have been on again. So, check your extensions and try to disable all of them or some of them or one by one. Good luck!