Hi vtverdohleb!
I'm using plex server 1.18 on my dns 327l as backend of my kodi istances.
I'm wondering, if I'll upgrade to the last plex server, what I have to do to restore my database?
The media database is preserved after the reinstallation of the addon. But the first launch will take a long time - from 10 to 30 minutes.
After the first run, you can not stop the addon until the database has been completely converted for the new version. If stopped, the high probability of damage to the database and, as a result, a complete re-scan of the media content.