After installing Fedora 31 I had some issues playing movies from Plex with the following error message:

plex error s4032 (manifest)

I solved the issue buy activating the RPM Fusion repositories:

sudo dnf install https://download1.rpmfusion.org/{free/fedora/rpmfusion-free,nonfree/fedora/rpmfusion-nonfree}-release-$(rpm -E %fedora).noarch.rpm

and installing ffmpeg compat libs:

sudo dnf install compat-ffmpeg28 ffmpeg-libs