Cant access Plesk, Error 'Can't open or create shared memory by shm.name, Permission denied'

Question

i got a problem with Plesk (Ubuntu Webserver),- i cant access plesk. I havent change anything before. The following error messages is shown:

Server Error 500 Plesk\Lock\Exception Lock Manager error: '[LockManagerException] Can't open or create shared memory by shm.name: "/run/lock/lmlib/SharedLockManagerStorage0.2.4"; shm.start_size: "8388608"; error "Permission denied"'.

I cant try: https://support.plesk.com/hc/en-us/articles/115003405193-Unable-to-open-Plesk-Lock-Manager-error-Can-t-open-or-create-shared-memory-by-shm-name

or

https://support.plesk.com/hc/en-us/articles/115002301654-Plesk-is-unavailable-after-upgrade-Can-t-open-or-create-shared-memory-by-shm-name

or

https://support.plesk.com/hc/en-us/articles/115000224773-Plesk-is-not-accessible-Can-t-open-or-create-shared-memory-by-shm-name

because i can currently only connect to Server via SSH when in rescue mode. (Dont know why ... idea how to enable/check SSH, so i can connect in normal mode ??)

How can i fix the problem when the rescue mode is running?

Greetings, Julian