Server Version#:Version 1.43.3.10745
Player Version#: 1.112.0.359-0d79a49f
I get the error in the title when trying to play any title out of the plex client for macOS using my m5 pro 14 inch MacBook Pro on Tahoe 26.5.2.
If I use the web client in chrome it will direct play everything fine. All my other clients on iOS, LG, and even the htpc MacOS client work properly. It is only the macOS desktop client that serves this error. I have attached the logs from both the server and the client. Please let me know if there is anything I can try to do from my end to help the plex MacOS client app work.
Plex Media Server.log (7.7 MB)
Plex.log (442.3 KB)
this is happening to me on multiple mac devices
unfortunately it doesn’t seem like anyone from plex really cares about this issue or the handful of other posts that mention it.
I was able to get things working again be deleting my security certificate on my Mac server, and then deleting the desktop app and all the remaining files in the user application support and cache directories and reinstalling the app.
Not sure if my method had anything to do with a fix or if plex instituted some sort of fix on their end.
how did you delete the security certificate?
The certificate is in the path below. You may need to press Command + Shift + "." to show the hidden folders/files.
The cert file is named certificate.p12 or maybe cert-v2.p12. Make sure plex is stopped/completely quit before removing it. I would move it out of the folder vs deleting it. Once done, start plex back up and give it a few minutes to settle and grab a new certificate.

Hey, that worked! Much appreciated!
My Plex server is installed in a Docker container on a linux system, but the file structure is the same. I moved out the certificate.p12 file, started the container up, and a new cert-v2 was created in the same folder.
I think that error had to do with recently migrating my Plex install to a new location, in my case.