Apparently since version v.1.41.5.9522-a96edc606 OS X 10.11 is no longer supported and 10.13 is the new ‘minimum’ version.
This was not mentioned in the change logs which I always check.
I ‘just’ wanted quickly to update and then watch something…
I was happy with the previous version. Why don’t you keep a few previous versions especially after a change like this?
Where can I find the latest version which does work in OS X 10.11. I do not know what my previous version was.
Mental note: never upgrade Plex from the UI, always manually since then at least you have the previous version still.
Check out ~/Library/Application Support/Plex Media Server/Updates for previously installed versions of PMS. I haven’t done that in some time… from what I remember, you should be able to unzip the package and replace the content of current app with that (right-click the app → show content).