The file is assigned // # sourceMappingURL, but already exists

Question

I just noticed that the Firefox console is displaying the following error for each .js / file. coffee in my project (even in packages).

-file- is being assigned a //# sourceMappingURL, but already has one 

Nothing is displayed in the Chrome console. I tried to delete all .map files and clear the Firefox cache, but I still get errors.

Answer 1

This is a warning (not an error) and this is an error ( https://bugzilla.mozilla.org/show_bug.cgi?id=1020846 recorded in FF 33)

This warning / error also applies to other libraries (angular, trunk, etc.)

Answer 2

I’ve been working on the project for over a year now, I’ve never seen this message until about the last Firefox update.

I got it using jQuery 1.9.x, so I just updated jQuery to 1.11.x and the error went away. I'm happy now.

So, if you are using jQuery and see this error / warning, try updating jQuery to the latest version.

Hope this helps someone.

Answer 3

On Firefox 27.0.1, I was getting this same error. I already have jQuery 1.11.0.

 SyntaxError: Using //@ to indicate sourceMappingURL pragmas is deprecated. Use //# instead kendo.dataviz.min.js:25 22:09:26.635 Error: http://localhost/project/Scripts/kendo.dataviz.min.js is being assigned a //# sourceMappingURL, but already has one 

I opened kendo.dataviz.min.js and deleted the offensive line:

 //@ sourceMappingURL=kendo.dataviz.min.js.map 

Answer 4

enter the code inside

  $( document ).ready(function() { //whatever }); 

then the message disappears.

Answer 5

For people using Visual Studio 2013 and downloading jQuery libraries through NuGet , check out your jquery-xxxmin.js and you will find the text comment below that issues this warning on Firefox .

 // # sourceMappingURL=jquery-xxxmin.map 

You can safely delete these lines.

Answer 6

Update jquery - from jQuery http://www.jquery.com/download

You can also download the sourcemap file for use when debugging a compressed file. A map file is not required for jQuery user to run, it just improves the development debugger. Starting with jQuery 1.11.0 / 2.1.0 the comment // # sourceMappingURL is not included in the compressed file.