Errors adding subscriptions on back end

Membership Pro: 2.8.3
Joomla: 3.6.5

If I try to add a membership on on the back end, I get errors. After clicking the "New" button and getting the to the subscriber form, I get a popup that just says "Error" with an OK button. If I select a user the fields no longer auto-populate. The state drop down is not populating either.

Essentially, the form is not usable and I can't add subscribers on the back end.

Anyone else having this issue?

I actually found that Event Booking is having exactly the same issue adding Registrants. I am looking to see if there is something running site-wide affecting this. In the meantime if anyone has a thought on this, please let me know.

I just found Event Booking on a completely different website having the same issue.

Has anyone ever seen this issue? I can't figure out what is going wrong.

Hello Eric

Look like there is something causes AJAX request error. Please submit a support ticket sending us super admin account of your site so that we can check the issue directly on your site to see why it happens and get it sorted

Regards,

Tuan