Big Sur does not let me switch users

I have an admin user and a standard user on Big Sur. I can log on to either when booting up but if I log out of one user the system will not accept the password for the other. I can sleep the machine and successfully enter the password for the current user on wake up.

I set up a test user and the result is the same for this. I have run First Aid in Disk Utility and run an SMC reset with no result.

This might be a Keychain issue but I am reluctant to reset the keychain because I have no idea what that might affect. Also each user has its own Keychain so it isn’t clear why all should be affected.

Any suggestions?

Update:
Updating to macOS 11.4 changed the problem. Everything works correctly when I use a wired keyboard but with a Bluetooth keyboard (I tried a couple) the system does not recognize certain keys (9 of them) when typing the password for switching users. This is bizarre!

Go to system preferences/keyboard/input sources. You can check your keyboard profile there and add additional ones. check “show input menu in menu bar”. You can select between your input sources here and also display the keyboard map. It is possible that you have a different configuration of external keyboard. Knowing nothing else, just a guess.

Also, this might be a soapbox, but I have so few problems that I always advocate this. do a clean install, especially going to a major update in OS. Backup all your files - if you have cloud backup - you are partially there already, create a bootable disk, download the MACOS system installer, do a system recovery, reformat your SSD, and install MACOS. this ain’t windows, the whole process should take under an hour.

It actually had to be done for me only once. Somehow I got a bad Dylib and Safari was crashing. I took the hour, and everything was fixed. take the time to clean up a lot of crap you don’t use anymore, you will thank me for that.

Thank you replying. Actually, I had checked the keyboard profile before and found nothing surprising. I ran a complete factory reset of all Bluetooth devices (option-shift click on the Bluetooth icon) but no change, same 9 keys fail to register on both keyboards.

I agree a clean install is a good idea but I have customized so much over the years that I don’t know if I’ll get it all right. Maybe one day, or I’ll wait until I buy a new machine.

Yeah…but it isn’t as easy as you think. Lots of apps from App Store so loading them is easy…but without migrating you lose all the preferences, list of frequent locations and customization. Then there is the 2 or 3 dozen that aren’t App Store to be downloaded and installed and customized…so you have a much more than 1 hour effort. And then you have the half dozen of needed but I forgot to add them utilities to get, pull up the licenses, etc.

Does it help? Sure…sometimes.

Is it quick or easy? Nope.

Agreed. I have a list of instructions for installing everything from scratch, I’ve done it on other machines with fewer apps etc. but never on my main machine (a 2014 27" Retina iMac). I think I’ll wait to see if Apple announces a 27" Apple Silicon iMac, unless they decide that the 24" is big enough.
WhenI switch users I just have to plug in a wired keyboard to enter the password, I can live with that, or change the password to use the keys that actually work.

Well it is very quick and easy for me, maybe that is why I don’t have problems. Are you saying you can’t backup and restore? seems odd. there are not that many locations where your preference data is stored, and you can easily backup your applications. If you have made it complicated, may time to rethink a bit. Personally, I use the event to clean up all the crap I don’t need anymore, my preference data is all iCloud, and last time I had a few programs that needed me to re-login, but you know - Keychain, so that was easy.

I’m sure it could be made difficult, and I am sure there are people doing way more complicated stuff than I do to which it may be harder, but that is all the more reason to make it simpler. Imagine losing all that stuff to theft or a fire, or the Pepsi syndrome.

No problem with backup and restore. I have two Time Machines working in parallel, an offline backup copy of all files, and a cloud backup of everything (Backblaze). However, for a clean start my plan would be to restore all my documents, photos, audiobooks, music, videos, etc. (which takes hours as there is 0.5Tb of this) and perform new installs of all my apps and utilities manually. I would not restore from Time Machine or a Carbon Copy Cloner backup because that could bring along some old junk too.

Anyway, it’s far too much work just to find out whether it solves my original problem of entering certain password characters via a Bluetooth keyboard.