Do you know what version you had updated to? Looking at your account the server that has not been seen for 7 days (that appears to be at a hosting provider) that should be updated. Important Security Update for Plex Media Server v1.43.2 and earlier
if you did update I would maybe try to restore a database backup as it being corrupt may be the cause of the error.
If you have filesystem access may need to see the server logs.
