My Mac running Mojave is not starting up. I get as far the Apple logo and progression line. Freezes there.
this is happening after I tried to upgrade to Catalina. This has proven to be a bad idea. I waited to try to do a safe mode start up and back out of Catalina back to Mojave.
any idea?
thanks
carlos
[Re-Titled by Moderator]
iMac 21.5″, macOS 10.14
Two most likely possibilities are an issue with some third party installed software, or a hardware failure most likely with the hard drive.
Try booting into Safe Mode to see if that can allow you to log into it & finish the OS install.
Try running the Apple Diagnostics to see if any hardware issues are detected. Unfortunately the diagnostics rarely detect problems even when a hardware issue has been confirmed through other methods.
You can try installing macOS to an external USB3 SSD, then boot from the external SSD. This will tell you the basic hardware is working fine with the possible exception of the internal drive. At least if you can boot macOS from the external drive, then you will have an easier time to try to troubleshoot the issue such as checking the health of the internal drive. Plus if you don't have a backup, then you may be able to attempt to recover some data (check the health of the drive first since a failing drive will just get worse the more you try to access it.....macOS & data recover apps don't handle the I/O errors of a failing drive anyway).
You should also disconnect all external devices just in case one of them is causing a problem.
Safe startup failure after Catalina upgrade on Mac Mojave
