Some users reported that after upgrading to iOS 16.3, several Apple iCloud services could not be synchronized.

CTOnews.com February 7 news, some iCloud users reported that after upgrading to the new version of iOS 16.3, applications such as iCloud Drive and Photos were unable to synchronize. Foreign science and technology media AppleInsider initially believes that it is caused by the lack of two-factor certification.

In Apple's official support forums and Reddit community, many users reported that iCloud had a synchronization failure after upgrading to iOS 16.3. Services, including iCloud Drive and iCloud Backup, will receive an unexpected error during synchronization. Please try again later.

CTOnews.com learned that the iOS 16.3 system mainly introduces a new Apple ID security key function. Apple said the optional security features were designed for individuals who want "additional protection against targeted attacks such as phishing or social fraud".

When enabled, logging in to Apple ID requires entering the user's account password and then using the security key of FIDO authentication to complete two-factor authentication instead of the traditional six-digit verification code from another Apple device.

At present, most of the users who reported the above synchronization failures did not enable two-factor verification. Subsequent reports suggest that enabling two-factor authentication for Apple ID may be a solution, but not everyone wants to enable this security feature on their accounts.