com.apple.buildinfo.preflight.error 21 on macOS Monterey installation
For anyone out there trying to reinstall Monterey OS and getting this error, as I was, try first erasing the hard drive using the disk utility and then reinstalling the OS. That was the only way I could get past that error messsage.
Hope this helps someone, I spent over 2 hours researching this error before I discovered the solution.
[Re-Titled by Moderator]
Mac mini, macOS 12.7