It could also happen if your Mac account password was changed in some other way. However, the Keychain password didn’t change, and still uses your old Mac account password. You change your Apple ID password, which changes your Mac account password. Your Mac user account password is tied to your Apple ID account. Most of the time, this all happens behind the scenes, and you don’t see this type of screen. That feature itself is locked by the Keychain password, which is usually the same as your login account password (the password you type to login to your user account on the Mac).
The Keychain gives out the correct password for applications that need it. “Keychain” is just the Mac’s word for the feature that collects and saves all the passwords you use on your computer. I don’t know what Keychain is and I can’t get to my desktop. After I log into my computer, I get this message.
