# Mkv files not do not play
**URL:** https://forums.plex.tv/t/mkv-files-not-do-not-play/938521
**Category:** Plex Media Server
**Tags:** server-synology
**Created:** [May 2, 2026, 8:25pm UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521 "2026-05-02T20:25:41Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@jidlo](https://forums.plex.tv/u/jidlo)
#### Post date: [May 2, 2026, 8:25pm UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521/1 "2026-05-02T20:25:41Z")
Server Version#:Synology DS920+
I replaced my Bell Giga Hub 2.0 modem/ router due to the PMS connection issues. I can now access my Plex server on Synology NAS. All is good, but unlike in the past, I am now unable to play any mkv files. They can be played with VLC player, but not with Plex. What am I missing?
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### Author:  [@FordGuy61](https://forums.plex.tv/u/FordGuy61)
#### Post date: [May 2, 2026, 9:09pm UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521/2 "2026-05-02T21:09:26Z")
Which client are you using? Plex Web, Plex Desktop, mobile app, etc.?
What happens when you try to play something? Spinning circle, error message, something else?
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### Author:  [@jidlo](https://forums.plex.tv/u/jidlo)
#### Post date: [May 2, 2026, 9:25pm UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521/3 "2026-05-02T21:25:24Z")
Plex Web, Plex Desktop, mobile app all the same. I can only see a faded image of the file and a spinning circle. No error message.
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### Author:  [@jidlo](https://forums.plex.tv/u/jidlo)
#### Post date: [May 2, 2026, 9:52pm UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521/4 "2026-05-02T21:52:23Z")
On my S25 mobile the screen turns actually black after atte4mpting to play mkv.
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### Author:  [@PunkleJones](https://forums.plex.tv/u/PunkleJones)
#### Post date: [May 2, 2026, 10:46pm UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521/5 "2026-05-02T22:46:56Z")
FLV should newer be used to test video files as it plays " anything". Use something like "Media Player Classic Home Cinema (Mpc-hc) as it is much more “critical” to bad videos like plex players.
[Releases · clsid2/mpc-hc](https://github.com/clsid2/mpc-hc/releases)
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### Author:  [@jidlo](https://forums.plex.tv/u/jidlo)
#### Post date: [May 2, 2026, 11:40pm UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521/6 "2026-05-02T23:40:35Z")
Thanks. To clarify, my .mkv files play fine in other software, including VLC. The issue is specifically with Plex, which is what I’m trying to resolve.
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### Author:  [@trumpy81](https://forums.plex.tv/u/trumpy81)
#### Post date: [May 3, 2026, 12:56am UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521/7 "2026-05-03T00:56:13Z")
The problem is less likely to be the container (matroska aka .mkv) and more likely to be the codecs used to encode the video/audio.
Use ‘Getnfo’ in Plex to view which codecs your file/s use and then use Handbrake or similar to change the codecs to more suitable ones.
H.264/AAC in an mp4 container is the most supported file format to use for video files.
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### Author:  [@jidlo](https://forums.plex.tv/u/jidlo)
#### Post date: [May 5, 2026, 6:31pm UTC](https://forums.plex.tv/t/mkv-files-not-do-not-play/938521/8 "2026-05-05T18:31:36Z")
Hi. Thanks everyone for your help. I am now up and running my Plex with .mkv files. I adjusted some Transcoder settings within Plex and downloaded the Plex desktop app for windows. Still unable to play using URL, but as I understand, that is normal.