When trying to log in to the Control Panel, a customer gets an error like the below one:
CauseThis exception appears when the client's ID is absent in a session.
To fix the issue, you may want to perform the following:
1 - Switch web server for Panel to the Apache one:
%plesk_bin%\reconfigurator.exe --switch-plesk-web-server --new-provider=apache
2 - Check if the "psaadm" user has full access to the directory specified as session.save_path in %plesk_dir%\admin\php.ini.