I experienced the exact same problem as thread starter. KurzBaginski (@kurzbaginski)
I had to roll back to 2.8.6 to make everything work normally again.
However, with version 2.8.6 my server security software is now showing me the following message:
WordPress Ultimate Member plugin <= 2.8.6 – Authenticated (Contributor+) Stored Cross-Site Scripting vulnerability
Hopefully the Ultimate Member support team can fix this bug ASAP.
Thread Starter
tr2452
(@tr2452)
Thanks.
I was able to solve the problem with your suggestion.
It is unfortunate that the last plugin update caused this error.