// EDIT:

This error was caused by the Firebug extension in Firefox.

I would recommend anyone that uses this ext to disable and remove it immediately!

From a fresh composer setup, I receive a lot of js errors in both the backend and frontend. In the backend this actually breaks the navigation, does not load the products or order grid, so pretty much completely breaks the backend.

I tried 2.1.0 and 2.1.1, both seem to have the exact same issues. 2.0.7 did not have these issues. No extra modules installed, just a clean, fresh composer setup. I tried deleting cache dirs and re-deploying the static-content, making sure the user and file permissions are correct, but the missing files are never generated. The browser cache was flushed and pages force reloaded:

BE errors:

404 Not Found:


and sometimes:



TypeError: ko is undefined (knockout-es5.js (line 428, col 5))
ko.track = track;

TypeError: utils.extend is not a function (class.js (line 129, col 30))
child.defaults = utils.extend({}, parent.defaults || {});

These .js files are never even created in the above path in the magento-ui.

enter image description here

instead I think the files now reside in js/lib/view/utils/ instead of js/lib/registry/. So the error may be in the Magento magento/module-ui version 100.1.0.

enter image description here


404 errors:


However, the FE errors dissapear after a few reloads, sometimes at least?

other error is the same as in the BE:

TypeError: utils.extend is not a function ( class.js (line 129, col 30) )
child.defaults = utils.extend({}, parent.defaults || {});

I have not been able to find any bug reports on this and no fixes.

Test System:

  • Docker container Debian 8
  • Server version: Apache/2.4.10 (Debian)
  • PHP 5.6.24
  • MySQL Community Server 5.6.32
  • Did you try to deploy the static content? – Mukesh Sep 6 '16 at 9:47
  • Yes, as mentioned above: " I tried deleting cache dirs and re-deploying the static-content, making sure the user and file permissions are correct" – tecjam Sep 6 '16 at 9:52
  • Please try once to redepoly static content after removing everything, except .htaccess file from pub/static folder. – Mukesh Sep 6 '16 at 10:01
  • Did that, checked the file owner (all still the same as the rest of the files) and the missing files are not generated in the folder. Backend grids still do not load. Version 2.0.7 has no such issues. – tecjam Sep 6 '16 at 12:13
  • @tecjam put your comment as an answer this is the firebug issue if you are running firefox version > 50 then you have to disable the firebug same thing causing me issue – Murtuza Zabuawala Nov 3 '17 at 5:36

The issue is a problem with the Firefox Firebug add-on. If you still use it, you should disable it and use the Firefox devtools.

Firebug has officially been deprecated.

Please see: https://getfirebug.com/

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