Password error on contacts syncing

There are a few reasons you could be seeing a password error on attempting to sync your contacts.

  1. Your username/password is wrong. Check caps lock isn't on, and for common visual errors like mistaking a 0 (zero) for an O (capital o), or a 1 (one) for an l (lowercase letter L).
  2. You used your 2FA credentials or your account password. You need to use an app password for CalDAV or CardDAV access.
  3. When syncing with an external service (not just to your device), and your external account has two-factor authentication enabled, you need to generate an application password.

Here are instructions for generating application passwords for popular sites you might be syncing your information with: