Okay, I have a weird problem and hope someone might know the solution:
Since yesterday the backend of a TYPO3 site I'm working on is broken. I can log in normally, but when I then select one of the functions in the left menu (no matter which one) this will happen and nothing will work any more afterward:
Initially, there's just the second menu, the third one appeared when I tried clicking through all the functions in the hope this would change something.
Sometimes an error appears:
"Page tree error
Got an unexpected response from the server. Please check logs for details."
But of course, I can't access the logs...
Clearing the browser cache, restarting the browser in save mode without any plugins, log into another user account - nothing works, the result is always the same.
Does anyone have any idea how to get out of this again? Apparently other users still can work fine with the page, so it seems as it's not a general problem with the installation.