iOS 16.3 appears to be forcing some users to protect their accounts with 2FA

For most users, iOS 16.3 was an incidental upgrade, bringing important security updates and fixes along with a few new features, including support for security keys for Apple IDs. But some users are reporting a problem connecting to their iCloud Drive and Backup—and the problem appears to be related to two-factor authentication.

Apple hasn’t officially responded to the issue, but a few Apple Support Community posts and other online forums outline the problem. After upgrading to iOS 16.3 and iPadOS 16.3, several users are seeing an “Unknown Error” message when trying to back up to iCloud or sync with iCloud Drive. According to the post, the toggles for each feature were shut off and trying to turn them back on resulted in the pop-up error message. 

There appears to be a fix, however. Nearly all of the affected users have two-factor authentication turned off on their iCloud account and turning it on solved the problem. Apple requires 2FA for some Apple ID features, including Apple Pay and Sign in with Apple, but previously allowed Backup and Drive access without turning on the extra layer of security.

The change could be related to Advanced Data Protection, which arrived in the U.S. with iOS 16.2 and expanded to the rest of the world with iOS 16.3. The new security features enable end-to-end encryption for iCloud Drive and backups and require a Recovery Contact or Recovery Key set up on your account. It’s possible that Apple has also added a two-factor authentication requirement as well.