Monterey Install Stalled at "less than a minute"

Do you have an Apple SSD installed? The Monterey upgrade includes and update to the Mac's firmware and during the upgrade the installer looks for an apple SSD to temporarily write some information necessary for the installer to do the Mac firmware update. If no Apple SSD the upgrade terminate with different error messages or just freezes.

Some users have problem with skipping upgrade versions and even not updating to the latest version of Big Sur. If you have an Apple SSD and are not fully updated Big Sur then, if on Big Sur fully update Big Sur and try upgrading to Monterey again. If older than Monterey then I would incrementally upgrade in macOS sequence one upgrade version at a time since some other upgrade includes Mac firmware updates. You can get older versions here:

How to get old versions of macOS - Apple Support

How much free space on your mac?

Not enough space is probably the most common reason for updates failing.

Depending on what you are upgrading from, you may need some 40GB+ of free space.

Like Reggie, my iMac 27inch is stuck, it’s not getting past the restart installation so I can’t even try these options above. Safe mode didn’t work, I ran disk repairs, and reset the PRAM but it still stays stuck at the point with the apple logo and the load bar fully loaded. Longest count I’ve left it is 9 hours. I forget which OS I was on, but all I saw was security update rather than an OS upgrade when I started the process so I’m limited in accurate information unfortunately.

should I expect a refurbished iMac from 2014 ish to possibly take a lot longer? Just need to know expectations and I can tell my work.

thanks!