No, Plex doesn’t touch the files again after they are recorded.
It’s possible there was a change in the way thumbnails are generated but I’m not aware of any. I’ll check.
Actually, if you still happen to have that file or run into another file that causes the problem, or someone else who is having this issue, if you can rollback to previous versions and figure out which version the crash starts on, that would help identify any changes. If you have a small file that can reproduce, provide me that file. Thanks.
Random (possibly crazy) thought: looking at the logs, it appears Plex uses ffmpeg to generate the thumbnails. If this is correct, is there any chance that ffmpeg was simply updated in a recent plex release, and that the new version is less tolerant?
I’ll see if I can find the time to try that, perhaps over this weekend. In my case the file is 221.7 MB (actually, quite a bit smaller than other episodes which weigh in at around 600 MB), so not really small, no 
Ah yes, you are correct. There was a change to ffmpeg in 1.25.0. Sorry, we are up to 1.25.1 and was thinking any changes would have already been seen in 1.25.0.
If I can get a file to reproduce, I’ll pass it along to our ffmpeg guru to take a look.
That’s fine. I just don’t want a multi-GB file. Can you upload to Google Drive or similar and send me a link.
Got it, thanks.
Here’s the same file that crashed for me:
Got that too. Thanks
@ibrewster I can’t finish uncompressing that file. It’s stuck at 99% 0 bytes left. I think your file might be missing the EOF (end of file) marker. This could definitely affect the thumbnail generation as it won’t know to stop reading the file and ends up reading junk since it won’t be video data.
Version 1.22.3.4523 was the last PMS version that worked on my Mac mini running Catalina. Versions after that crash when generating video preview thumbnails.
Where do you go to get the previous versions?
Interesting. There’s nothing in 1.23.0 (that’s what came next after 1.22.3) related to ffmpeg or thumbnail generation.
Ok, I was able to reproduce the crash with the 2 samples I got. Boy are these files bad.
Here are my log files as promised. I was not sure where to look for the offending video files tho. The server crashed on the 9th.
Plex Media Server Logs_2021-12-10_09-10-48.zip (4.0 MB)
After removing these files, I can report that last night was the first night in several weeks that my PMS did not crash. Thank you for finding the culprit but hopefully PMS can be a bit more tolerant to bad files.
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Ditto here. No crash (somewhat to my surprise), but still hoping the underlying issue can be fixed.
@leejk Looks like Chicago P.D. (2014) - S05E13 - Chasing Monsters.ts
@vlord3 and @ibrewster Thanks for the confirmation. Yeah, I’m following up with our transcoder expert to see what can be done.
Ok. That is a recorded file by Plex. I have noticed that the recorded video is wonky on playback. Sometimes you can’t skip ahead to fast forward past a commercial. For example, if you press the right arrow on the remote three times or so to skip ahead, it might in fact go backwards. Or an hour show may say that it is 7 hours in length. So I am not surprised this video is causing the problem, as they are terribly encoded files to begin with.
