Hello PrzemekM !
I am not so skilled, but I can give you my experience with this issue.
It appeared that my main disk was too full :-(
I deleted a couple of unnecessary files (old time backups) and everything worked well again... and is still working.
I hope it helped.
All the best.
JCZ
Hello!
After a reboot, because I could'nt anymore access to my Plesk manager (after ID and PW entry, I had only the refresh of the ID/PW input page), I get this message.
ERROR: PleskFatalException
Unable to connect to database: mysql_connect() [<a...