Server Version#: 1.30.0.6486
Player Version#: This happens when playing back on current Roku or Apple TV players
When streaming 4K content on a 1080P player, I am seeing transcoding fail with “No space left on device”. The transcoding temporary directory is set to a drive with about 720Gbytes free. I have seen this with 4K from Raya and the Last Dragon (current logs) and Thor - Love and Thunder.
There is a bug in 1.30.0 and 1.30.1 when transcoding TrueHD audio.
The workaround is to choose a different audio track, if available, or to fall back to 1.29.2 or earlier.
If you do not have the 1.29.2 installer, look in the Updates folder of the Plex Data Folder on your system (%LOCALAPPDATA%\Plex Media Server\Updates). Plex keeps a limited number of older versions in that location (not sure of exact number).
Plex is aware of the problem. Unknown when a fix will be available.