I am actually seeing this same issue. It is also an H265 Dolby Vision file, trying to play in the Chrome player.
Downgrading PMS to 1.25.4 resolves the issue. Any PMS version at or above 1.25.5 results in the “Color space is not supported” error.
Logs here: Plex Media Server Logs_2022-03-19_13-09-39.zip (3.9 MB)
I have the same specific error:
Mar 19, 2022 10:48:49.529 [0x1473cebd1b38] DEBUG - [Transcode] Streaming Resource: Reached Decision id=44368 codes=(General=2000,Neither direct play nor conversion is available. Direct Play=3000,App cannot direct play this item. Direct play is disabled. Transcode=2003,File is unplayable. Color space is not supported.) media=(id=85931 part=(id=86057 decision=none container=mp4 protocol=dash streams=(Video=(id=217455 decision=transcode bitrate=2147483647 encoder=h264_vaapi width=1920 height=1080) Audio=(id=217456 decision=transcode bitrate=256 encoder=aac channels=2 rate=48000) Subtitle=(id=217457 decision=transcode bitrate=2147483647 encoder=ass languageCode=ita location=sidecar))))
