Steps to reproduce the issue

Create a com_content custom field and edit an article from the front end.

Actual result

The browser console reports this error:
jquery.min.js?b2ad6c9…:3 GET http://localhost/media/jui/images/ajax-loader.gif 404 (Not Found)

Expected result

Path misses (in my case) the j37 folder element as in: http://localhost/j37/media/jui/images/ajax-loader.gif