ffmpeg h264 conversion failure - Error: stderr maxBuffer length exceeded

[mokahless]

Describe the bug
Preamble: I can't be 100% sure but my guess on the cause is ffmpeg running for too long. Run time was 3h39m before it just stopped about halfway through. Custom settings were FFMPEG_OUTPUT_ARGS=-preset veryslow -crf 23 -threads 3. encode/upload retention was set to 8 days.
Was hoping to use this as a front end for slow, long conversions with reduced CPU usage due to not wanting to interrupt the main processes on my server.
20GB free RAM, 6 cores, 80GB free space. original file 500MB, output 1GB (low quality source, but was just for testing anyway) or rather 433MB because it did less than half.

Error:
WebUI: "Failed, check logs" - It did convert 3m47s of the ~8m clip, 1920p, 12fps

[libvorbis @ 0x557638fd2040] Queue input is backward in time convertx | frame= 2630 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.50 bitraframe= 2630 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.50 bitrate=15611.6kbframe= 2631 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.58 bitrate=15605.7kb[libvorbis @ 0x557638fd2040] Queue input is backward in time convertx | Last message repeated 2 times convertx | frame= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitraframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kbframe= 2632 fps=0.6 q=26.0 size= 418304KiB time=00:03:39.66 bitrate=15599.8kb[libvorbi=0 drop=5 speed=0.0519x convertx | Failed to convert ./data/uploads/1/7/test.mp4 from mp4 to h264.mkv using ffmpeg. error: Error: stderr maxBuffer length exceeded convertx | error: NOT_FOUND convertx | status: 404, convertx | code: "NOT_FOUND" convertx | convertx | at NotFoundError (/app/node_modules/elysia/src/error.ts:130:3)

To Reproduce
Change settings so on your system so the process runs for 4h or more and observe error.

Checklist:

reverse proxy https