All of the Plex versions and updates since you’ve installed it are kept in:
/Users/YOUR-USER-NAME/Library/Application Support/Plex Media Server/Updates
Find the version you’re looking for, go into that folder then go into the folder called Packages. You’ll see a .zip file that looks something like (depending on the version you’re looking for):
PlexMediaServer-1.23.0.4482-62157842a-macos-x86_64-standard-full.zip
Copy (not move) the zip to a temporary folder (like Downloads) and unzip it. It will have folder named “Contents” (with a bunch of things under it)
Stop your Plex Server application.
In Finder, go to your Applications folder. Right click on the Plex app and choose “Show Package Contents”
You’ll also see a Contents folder (how bout that!). Rename the Contents folder to Contents.old and then drag and drop the Contents folder you unzipped into it. Close the finder window then Run the Plex app. You’ll be on that previous version.
