I recently upgraded to a new PC and was moving my Plex media server to my new desktop. I installed PMS on new system and copied LocalData files from original source. All media was on external hard drive, so I just moved it over to the destination system. All movies are there and playable from the Plex media server via web browser. But, when I go to Apple TVs in other parts of the house, mkv files will not play ("Playback was terminated by the server. Conversion failed. The transcoder crashed or failed to start up."). Other files play just fine (mp4, avi, etc).
I am using Version 1.8.4.4249. I have had PLex for a few years, but have an extremely limited knowledge base. I know someone will ask for a log.....I hope I included what is necessary.