I have had some users see the error 2 as well, but not specifically just on M1. It has happened randomly for different users on Window and Mac (both Intel and M1). Overall, a pretty low percentage of users though… for sure <5% and probably <1% of users report this error.
I typically ensure their creative cloud app is running the latest release and then have them restart their computer. Sometimes restarting the computer fixes it and sometimes it doesn’t. For the cases where it doesn’t fix it I send them to Adobe support because there is nothing I can do at that point.
For every case except 1, Adobe support was able to fix it and install with the same CCX files. The users have never been able to tell me what Adobe did to fix it but I would really like to know if it is something that I could do in these cases without needing to refer them to Adobe support.
In one case, Adobe support couldn’t fix it so the user just continued to use the old CEP version of my program instead. I’m not sure if he ever got the UXP version installed. I still need to follow up with him.