Roundcube broken after update

Hi,

My Roundcube installation is broken after an update. It says:

SERVICE CURRENTLY NOT AVAILABLE!

Error No. [520]

But whatever I do, reinstalling, deleting all files and install it again, it’s just saying this.

Is there a way to debug this? I saw some other topics with the same issue, but all of these didn’t fix mine.

Thanks in advance.

Kevin