Even if you have a 4k tv, and your streaming device is capable of streaming 4k doesn’t mean that you can stream 4k from plex; there is a difference between the streaming services’ compressed 4k video and uncompressed blu-ray quality 4k video; in order to play 4k content from plex you need at least 50Mbps for web-dl 4k rip and 100+ Mbps for remux 4k also a suitable streaming device that can play 4k video and audio without transcoding, good HDMI cable otherwise you will get an error like this.
Here’s how you can fix it first, check if your tv or sound system audio output is 2 channel stereo. if it’s 2.0 You can’t play 4k without enabling audio transcoding for your account, and if it supports 5.1 surround sound, you can make some changes and play the video without getting errors.
If you see any movie that has TrueHD 7.1 audio, and if you don’t have a Navida shield or sound system capable of playing 7.1 but can play 5.1 surround sound, click on More>
than Playback settings> Select audio stream
And select the other audio stream from there. It will get rid of the error, but if you still get errors, please contact support so we can figure out what’s wrong on your side.