About two weeks ago, I installed the iOS 27 public beta to try it out, then restored my phone to the latest signed version of iOS 26 using the Apple Devices tool. Since the downgrade, I can't reliably sign in to iCloud on any device. Photos, notes, and messages stored in iCloud also won't sync to my phone. On iCloud.com, I can enter my credentials successfully, but I'm logged out and returned to the sign-in screen within a couple of seconds. Apple Support has been investigating for more than a week without finding a solution. Has anyone dealt with similar iCloud problems after downgrading from a beta?
2 Answers
Downgrades can occasionally cause problems with shared iCloud data even when the downgrade itself completes successfully. Since the issue affects iCloud.com and multiple devices—not just one phone—it sounds more like an account or server-side session problem than a damaged local restore. Returning to the beta might be a useful diagnostic test, but it isn’t guaranteed to restore access, so I’d avoid repeatedly restoring the phone until Apple finishes checking the account.
A backup created or updated while running iOS 27 may not be restorable to iOS 26. Downgrading can also leave some iCloud-related data in an inconsistent state, especially if the phone was restored rather than updated normally. That doesn’t necessarily explain the iCloud.com login loop, but the version mismatch is worth checking carefully before trying another restore.
I followed Apple’s instructions and made a final backup on iOS 26 before installing the beta. Once I moved to the beta, I also turned off iCloud Backup, so I don’t think the current backup was created on iOS 27.

Would upgrading back to the beta potentially make my iCloud photos visible again, or could that make the situation worse?