I maintaine the web site of a friend of mine, and the console logs the following error:
GET https://www.my-client-site.ext/undefined 404 (Not Found) undefined:1
The problem is that I can't find the location of this call in the page.
I have try to search the page source code, and I cannot find any referense to this URL.
Also I have try to check JS files with break points, and still I cannot find this issue.
Is there any other way to make reseach for this particular issue ?
Go to firefox and install addon called Firebug.
https://addons.mozilla.org/en-US/firefox/addon/firebug/
Now Open firebug and go to console tab, Firebug will show your javascript which is calling ajax in right corner of the pane.
Hope this helps.