LG WebOs “Unexpected Playback error” when transcoding

Plex Players
23

I think this is the same problem I outline here: [BUG] LG webOS 10.x - Playback Error 400 (HTTP Header Overflow due to Client Profile Bloat)

Here’s how I was able to fix the issues:

1. For MKV Files (Windows & Mac)

Use MKVToolNix (specifically the mkvpropedit tool) to wipe long internal names:

  • Command: Open Terminal/Command Prompt and run: mkvpropedit "filename.mkv" --edit info --delete title --edit track:v1 --delete name --edit track:a1 --delete name

  • Tip: Use a “for” loop to batch-process a whole folder.

2. For MP4 Files

  • Mac: Use Subler. Open the file → Metadata tab → delete Title. Go to Tracks tab → click Video/Audio → delete Name. Save (ensure “Optimize” is checked).

  • Windows: Right-click file → Properties → Details → click “Remove Properties and Personal Information” at the bottom. Choose “Remove following properties” and select Title and Comments.

  • Both (Fastest): Use FFmpeg: ffmpeg -i "input.mp4" -map_metadata -1 -c copy "output.mp4"

Final Step (Mandatory)

In Plex Web, go to the movie/show, click the three dots (…), and select Analyze. This forces Plex to update its database and shorten the playback URL.