Moreover, this happens ONLY if the user logged in.
No error when the user is a Guest Or Admin
I am encountering the same. we can’t add to cart because it is stuck to Wait… it happened after upgrading to 1.3.7 & 1.3.8 — it was working fine in 1.3.6
I tried to revert it to 1.3.6 and the error was gone (but the UI was messed up so I have to upgrade to 1.3.8 again) ..
In my investigation, the root cause of the issue is that the admin-ajax.php is returning 403 Forbidden when you click Add. It happens when the page is cache. if I purge the cache, it will work for some time, and then it will happen again. Please fix it..
