After making my own docker container this issue went away. I'm not sure if it's a env variable that was wrong on the pre-built app or the file output template (invalid characters) but here's what mine looks like and the output template string %(playlist_title&Playlist |)S%(playlist_title|)S%(playlist_uploader& by |)S%(playlist_uploader|)S%(playlist_autonumber& - |)S%(playlist_autonumber|)S%(playlist_count& of |)S%(playlist_count|)S%(playlist_autonumber& - |)S%(uploader,creator|UNKNOWN_AUTHOR)S - %(title|UNKNOWN_TITLE)S - %(release_date>%Y-%m-%d,upload_date>%Y-%m-%d|UNKNOWN_DATE)S.%(ext)s' hopefully this helps.