# MKV Codec missing on Truenas server?
**URL:** https://forums.plex.tv/t/mkv-codec-missing-on-truenas-server/899030
**Category:** Plex Media Server
**Tags:** server-truenas
**Created:** [December 16, 2024, 10:47am UTC](https://forums.plex.tv/t/mkv-codec-missing-on-truenas-server/899030 "2024-12-16T10:47:35Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Dick\_Waggles](https://forums.plex.tv/u/Dick_Waggles)
#### Post date: [December 16, 2024, 10:47am UTC](https://forums.plex.tv/t/mkv-codec-missing-on-truenas-server/899030/1 "2024-12-16T10:47:35Z")
Server Version#: 1.41.3.9292
Player Version#:
Recently spun up a new NAS on Truenas/HexOS and installed plex onto it and moved some stuff over for testing. For whatever reason MKV files refuse to run and I get “conversion failed, Codec not found or failed to install”. However the plex desktop app sometimes runs them, but the browser plex app never works and the mobile app fails most times as well. This has not been an issue with my other two servers. I’m guessing it’s something to do with Truenas but for the life of me i cannot find any real answers anywhere.
Trunas server is:
Intel I7-12700K
32GB DDR5 6000 ram
110TB Storage pool
[Plex Media Server Databases\_2024-12-16\_05-38-33.zip](https://forums.plex.tv/uploads/short-url/p5LPseIvP9HC3Zd1mq0TaBS3Fgs.zip) (1.6 MB)
[Plex Media Server Logs\_2024-12-16\_05-20-35.zip](https://forums.plex.tv/uploads/short-url/fLgX51SqFJjohTsNoHyl2XhCPqd.zip) (3.8 MB)
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### Author:  [@Dick\_Waggles](https://forums.plex.tv/u/Dick_Waggles)
#### Post date: [December 16, 2024, 11:51am UTC](https://forums.plex.tv/t/mkv-codec-missing-on-truenas-server/899030/2 "2024-12-16T11:51:03Z")
So i found a post saying that if you remove the .tmp from the Easy Audio Encoder folder and then delete the codecs folder that could help. Tried to load a few movies and now there’s a new zip folder that plex seems to have added on its own and I’ll be damned if mkvs didn’t start working again, heck even 4k is running well. Web browser app still doesn’t run terribly well, but I’m going to try the desktop app later since that seems to generally work better regardless
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### Author:  [@shark2k](https://forums.plex.tv/u/shark2k)
#### Post date: [December 16, 2024, 3:30pm UTC](https://forums.plex.tv/t/mkv-codec-missing-on-truenas-server/899030/3 "2024-12-16T15:30:07Z")
Just a FYI, MKV is not a codec but a container.
You would need to check to see what codec the video within the container is encoded with (AVC, h264/x264, h265/x265, etc.) to know what was missing.
Regarding the browser, that has a much better chance to require the files to be transcoded in order to view because support is more limited.
The desktop app is able to direct play a lot more stuff since it does not have the limitations the web browser does.
-Shark2k
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### Author:  [@system](https://forums.plex.tv/u/system)
#### Post date: [March 16, 2025, 3:30pm UTC](https://forums.plex.tv/t/mkv-codec-missing-on-truenas-server/899030/4 "2025-03-16T15:30:45Z")
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