SOLVED: Playback failed due to a fatal player error

[TheDreadPirate]

Jellyfin is almost certainly not using the correct ffmpeg.

Code:

[2024-08-08 11:35:01.850 +02:00] [ERR] [9] Jellyfin.Api.Middleware.ExceptionMiddleware: Error processing request. URL "GET" "/videos/c2d00ba0-8813-7170-4d93-2ee744aa4f62/live.m3u8".
System.ArgumentNullException: Value cannot be null. (Parameter '_mediaEncoder.EncoderPath')
   at System.ArgumentNullException.Throw(String paramName)
   at System.ArgumentNullException.ThrowIfNull(Object argument, String paramName)
   at System.ArgumentException.ThrowNullOrEmptyException(String argument, String paramName)
   at System.ArgumentException.ThrowIfNullOrEmpty(String argument, String paramName)
   at MediaBrowser.MediaEncoding.Transcoding.TranscodeManager.StartFfMpeg(StreamState state, String outputPath, String commandLineArguments, Guid userId, TranscodingJobType transcodingJobType, CancellationTokenSource cancellationTokenSource, String workingDirectory)

This is saying it can't access ffmpeg. Which means when Jellyfin is calling "ffmpeg" it is getting the other ffmpeg you have on your system and Jellyfin doesn't have access to it.

I'm not entirely sure how to change this in newer versions of Jellyfin since we locked down changing the ffmpeg path due to security issues.

I think you'd have to modify C:\ProgramData\Jellyfin\Server\config\encoding.xml and provide the full path to ffmpeg.exe in the Jellyfin Program Files folder.