Plesk is slow, however, there are enough system resources on the server.
ERR  Exception: Token validation failed: The license key 'PLSK.0000000' was not verified. Plesk will try to verify license key. Please wait for few minutes and try again. To manually run verification of license key click "Retrieve Keys" button in "License Management".
Pressing Retrieve Keys in Tools & Settings > Licence Management shows that the license is up-to-date.
grsecurity is used on a server.
/etc/sw/keys/instancesdirectory has permissions that differ from below ones:
# ls -la /etc/sw/keys/ | grep instances
drwxrws--- 2 root swkey-data 4096 Jun 2 2012 instances
Plesk bug with ID #PPPM-6573 fixed in Plesk Onyx 17.8 on April 17th, 2018.
For Plesk Onyx 17.8, install the latest Plesk micro-updates.
For Plesk Onyx 17.0 and 17.5, upgrade to the latest Plesk version.
If update is not possible for some reason, try the following
Connect to Plesk server via SSH.
Fix the permissions:
# chmod 2770 /etc/sw/keys/
# chown root:swkey-data /etc/sw/keys/
If grsecurity is used, make
psaadma member of
# usermod -a -G procread psaadm
Back up the file
# mv /etc/sw/keys/registry.xml /etc/sw/keys/registry.xml.bak
Regenerate the file by pressing Retrieve Keys in Tools & Settings > Licence Management.
Note: If it did not help, reinstall the license key at Tools & Settings > Licence Management > Install Key.