Plesk host / Plesk Control Panel / Plesk container is slow or unresponsive.Some services (for example RDP) can be unstable.Also migration of large number of subscriptions may stop with "Failed" status and referrals to psabackup.dll
A lot of session files (like 500,000) are contained in the folder "
Remove all files from the folder "
%plesk_dir%\\admin\\session ".The following command in
cmd.exe window can be used:
del /f/s/q "%plesk_dir%\\admin\\sessions" > nul