Transcoder error when using external subtitles (opensubitles)

Plex Media Server
,
1

Server Version#:1.42.2.10156
Player Version#: 4.152.0

Issue:
Playback fails with the error “Transcoder failed” whenever external subtitles are used (from OpenSubtitles or local .srt). No additional error is shown.

Repro steps:

  1. Play any video.

  2. Select external subtitles (OpenSubtitles or local .srt).

  3. Playback stops with “Transcoder failed”.

Notes:

  • Works only if subtitles are manually embedded into the .mkv (e.g., with MKVToolNix).

  • Happens on both public release and beta builds.

2

Same issue. Seems like all external subtitles have this issue, when burn–in is required.