MZFinance.BadLogin.MacAppStore_message error when signing into Apple ID
Solution 1:
Mavericks does not support asking for two-factor authentication. However, you don't need to disable two-factor authentication to log in to services which don't support it.
- Attempt to log in as usual. You will receive an error message which may vary depending on the service and version of OS you are using.
- Choose to allow the login on another device and note the code given.
- Append the code to your password, then log in again.
Solution 2:
I seemed to get this error because the mavericks Apple ID sign in popup doesn't know how to handle 2 factor authentication that is associated with my Apple ID. All you need to do is temporarily disable 2FA by signing in here and under the security section click edit and disable 2FA from there.
It's advisable to reactivate 2FA once you are done setting everything up and updated.