Occasional Transcode Issues

Plex Media Server
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Server Version#: 1.41.6.9685
Player Version#: Latest Roku - Latest Web App

Server is running on Windows 11.

I’m seeing issues with various files, but not all. The file can usually play fine, then at a specific point in the video the experience is interrupted. For example, when using the Plex browser app, the video plays, then freezes, and a few seconds later it continues playing as if nothing has happened. On a Roku however, the video stops playing altogether, and then starts prompting for the next episode.

Obviously this is rather annoying behaviour, so I have managed to find a file that this is repeatable so I could inspect the logs. I see lines similar to this each time the problem happens (again, this is across multiple files, but not all):

May 06, 2025 21:43:07.315 [32300] ERROR - [Req#d950b/Transcode/wi5e1ws6n4ttnq8ne2v4pjdx/ffd4f534-9a01-495d-976d-1a818ee65b61] [matroska,webm @ 000001f801561d00] 0x00 at pos 1548670933 (0x5c4ed7d5) invalid as first byte of an EBML number
May 06, 2025 21:43:07.323 [32300] ERROR - [Req#d950c/Transcode/wi5e1ws6n4ttnq8ne2v4pjdx/ffd4f534-9a01-495d-976d-1a818ee65b61] [matroska,webm @ 000001f801561d00] 0x00 at pos 1551638382 (0x5c7c1f6e) invalid as first byte of an EBML number

I have already completed a full reinstall of PMS, and tested the files that have this problem on another separate PMS server, which plays them just fine.

Any ideas, or further troubleshooting I can do?

Thanks in advance :slight_smile:

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That’s indicative of a corrupt file. Test that file on VLC to see if you can play that part. 0x00 at pos 1548670933 is 1.55GB, so if the media file is around that size and the movie hasn’t reached the end, then you’re looking at a truncated file.

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Okay so what’s different with this server and that other one? Can you list them? Is one retreiving the file locally while one is on a network? Coz losing acces to the file can also cause this. Maybe drive or OS going to sleep?

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Well that is interesting. Same issue occurs in VLC. Perhaps I missed something with the 2nd PMS server. Thanks for the tip!

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Is there anything I can do for the future, like plex checking to see if the file is corrupted prior to playing?

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No that’s essentially your problem, you have to make sure that your files are intact. Plex already does a lot. One way to truncate a file is to move/copy it to a different drive while the file is still downloading. If you’re using some automation in regards to file handling, I would check those, because that is likely the culprit.

That’s why good apps will download to the destination using a temporary hidden file first, and then, when it’s done, it renames the file to the actual name.

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Makes sense. I’ll go over the automation and see what I can do.

Thanks again!

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