This looks to be related to DVR recording schedule. Possibly to an EPG update
Can you go to the plex data folder and inside that /Plug-in Support/Databases
In the Databases folder there should be three files that start with tv.plex.providers.epg.cloud a .db .db-shm and .db-wal file. Back these files up somewhere just in case like put in a folder on your desktop then try to start the server up again without them in the Databased folder. If it launches, it should start rebuilding the guide.
Image is from a Mac but files should be the same
