after update my guest user needs a password, why?

RainForest1964 wrote:

What password does my guest user need to access my MacBook pro? This has never happened before. The password is not my password.

Did you try leaving it blank?

Did you try removing the guest and then reapply a guest user?

To delete an account you have to verify you are logged out of the 'guest,' from the  dropdown>Log out

Set up users, guests, and groups on Mac - Apple Support

You may need to provide more information like what version of macOS, what update (is it for app or system).

Irrespective of the above information, See if safe mode helps.

https://support.apple.com/en-us/HT201262

Note: Safe mode prevents your Mac from loading certain software as it starts up, including login items, system extensions not required by macOS, and fonts not installed by macOS. It also does a basic check of your startup disk, similar to using First Aid in Disk Utility. And it deletes some system caches, including font caches and the kernel cache, which are automatically created again as needed.