Cannot make a decision because either the file is unplayable or the client provided

I’m getting this error when I try to play some files with Plex.

These files play perfectly in any other players, e.g. VLC

Host Server

14.04.1-Ubuntu SMP Tue Jun 28 19:17:10 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Plex version

Version 3.27.1

Clients

Web in chrome and Roku

Results

Streaming Resource: Cannot make a decision because either the file is unplayable or the client provided bad data

Plex refuses to play

Expected results
Stream the video

ffmpeg info

Input #0, matroska,webm, from ‘/mnt/allmediadrives/media/movies/It (2017)/It.mkv’:
Metadata:
title : EVO
encoder : libebml v1.3.0 + libmatroska v1.4.1
creation_time : 2017-12-10 11:37:17
Duration: 02:09:11.10, start: 0.000000, bitrate: 4757 kb/s
Stream #0:0(eng): Video: h264 (High), yuv420p(tv, bt709), 1920x1080, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
Stream #0:1(eng): Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s (default)

Log Output

What gives?

well, since this is my second post in a row that no support person wanted to help on…

if anyone else has this issue, go find another product, or click analyze on the library.

Can you provide the XML from Plex?

I provided the logs. I fixed it myself, so no, I can’t provide anything else.

Can you explain what you did to fix it? Maybe I can work backwards and figure out what the original problem was.