I had macos 11.5 public beta 4 installed and upgraded to Monterey. The upgrade finished without an issue bringing me to the log in screen. I enter my credentials, I get a black screen for a couple of seconds only to return to the login screen. I boot in safe mode and manage to login but I am getting the WindowServer crashing. I removed all startup Apps and rebooted but the issue persists. I then tried to go back to Big Sur through Recovery mode and I get an error "The operation couldn't be completed. (com.apple.BuildInfo.preflight.error error 21.)", while at the stage of picking the drive to install it on (my primary ssd) Any ideas?
Ok - Here is what was happening. I have a Satechi USB-C hub connected on my MBP 16 and through HDMI a Dell U2415. I had a third party calibrated icc profile on it. Every time I was trying to login with the hub connected the laptop display would go out of sync resulting to the Windows server crashing and throwing me out in the login screen. Once I removed the relevant icc profiles from System preferences I was able to login normally