mac os Monterey
I tried to install Mac OS Monterey, and the message "checking '(null)'" keeps popping up, and I don't know what to do to get rid of it/ what it is actually doing.
MacBook Pro 13″, macOS 10.13
Try resetting your NVRAM/PRAM - Reset NVRAM or PRAM on your Mac - Apple Support
If that won't work, startup from macOS Recovery (CMD + OPT + R) and select "Reinstall macOS". This should install the latest compatible software, which in your case is Monterey. BACKUP STRONGLY RECOMMENDED!
