What operating system, is it 32 or 64 bit, what hardware are you running on and exactly which image did you use? linuxserver/plex is non specific, you need to provide the tag too.
Did you try the suggested image and tag linuxserver/plex:bionic ?
I am using a rpi4 so I guess it’s 32bits (armv7). I don’t know what happened but I was using always linuxserver/plex latest and pulling the image when needed to update
By changuing it to “bionic” it recreated sucesfully and everything works
What probably happened is that pulling linuxserver/plex:latest is no longer able to determine the system architecture and grab the appropriate image. Thus you may have gotten the amd64 tag which of course is very wrong for your hardware.
Also, if properly configured via the docker run, docker create, or docker compose command, there is no need to pull a new image to update to the latest version of Plex. Merely restarting the container will download the latest build into the already existing container. Read the image docs for how to set that up.