@serpevil there are several possible reasons behind this error:
1) You have unloaded jQuery on certain pages or site-wide and as a result any JS script dependant on jQuery will trigger the “undefined” error.
2) You have applied the “defer” attribute to jQuery, making it loading AFTER specific JS scripts are loaded that call jQuery (especially inline JavaScript)
3) You have applied combine JS and somehow, jQuery is loading AFTER specific scripts. This is very rare and it usually happens when there are exceptions added to the combined JS. If a JS inline script is triggering jQuery, and the jQuery library is added to the combined JS that is loaded AFTER that JS inline script, then the error will show up. This one is very rare, but we can’t exclude it.
Are you comfortable in sharing here the URL to your website / the page where you’re having this problem? We could check it out. It would be easier to do some debugging.
Solved. Looks like it was option 1. Thx for your time.
