Playback Error on Windows Plex Desktop App

Plex Players
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1

Hi,

I’m running into some issues after I was troubleshooting my plex libraries no longer showing up about once a day (resolved by restarting the Plex container on Unraid). I tried troubleshooting for hours this evening and had Claude poke around but could figuring out why my Desktop App playback was failing all of a sudden. Below is the summary:

Server: GMS, Docker (hotio/plex), Unraid, PMS 1.43.4.10903-e5521bd8c

Issue: Native Plex desktop app fails on all playback (direct play and transcode) with “An unknown error occurred (4294967283).” Confirmed across 3 separate Windows machines/users, after clean reinstalls. Web app (app.plex.tv/desktop), mobile, and TV apps all play fine, locally and remotely.

Key log line at failure:
CERT: incomplete TLS handshake from [client]: tlsv1 alert unknown ca (SSL routines)

Context: Server was unclaimed/reclaimed twice today (server ID/cert changed each time — have both old and new cert hashes if useful). Also saw repeated MyPlex: Error 403 requesting XML from servers.plex.tv and Mapped - Not Published states yesterday.

Already tried, no change:

  • Full uninstall/reinstall of desktop app (multiple times, multiple PCs)
  • Cleared local app data/cache, ran as admin
  • Restarted PCs
  • Verified system clock, disabled AV HTTPS scanning, checked proxy settings, disabled IPv6
  • Reclaimed server twice (new cert each time)
  • Deleted/rebuilt Codecs folder
  • Toggled hardware/software transcoding
  • Secure connections set to Preferred
  • Confirmed port 32400 open externally (canyouseeme.org) and via direct file/SMB access — files/storage/network all healthy

Not sure where to turn from here!

2

You can try to force the server cert to refresh. I know you claimed/reclaimed and the cert hash is different, but I’ve seen some where even in that case until the existing cert was deleted, it didn’t update properly.

Stop plex, go to the Cache directory in the Plex Media Server folder, remove (don’t delete) the *.p12 file, and start plex back up. It should download a new cert.