Your system crashed while updating lyrics and metadata during the maintenance period (look at last ~40 lines of Plex Media Server.2.log).
At the time, it was running 1.27.0.5873 (line 1, same file).
1.27.0.5889, which you installed today (Plex Media Server.log), has a fix for the problem (release notes).
See what happens during the next maintenance cycle. If Plex crashes again, pull a new set of log files.
