iOS 18.6.2 backup error: 'The last backup could not be completed' on iPhone

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Level 1

7 points

iOS 18.6.2 backup error: 'The last backup could not be completed' on iPhone

I’ve recently downgraded from iOS 26 to iOS 18.6.2. I’ve tried to backup my device (as it seems software update is being threatened) and I see the following error message:

The last backup could not be completed because iCloud contains a backup from a newer iOS version.

I’ve looked into the backups on my device, and it says last backup was never.

What can I do here to backup my device? I don’t want to upgrade to iOS 26.

[Re-Titled by Moderator]

Original Title: iPhone backup issue

iPhone 15 Pro

Posted on Sep 16, 2025 01:14 PM

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Answer 1

Sep 16, 2025 01:26 PM in response to sam_6

If you don't have a backup made before you updated to either iOS 26 Public or iOS Beta, you cannot make a backup of your data on iOS 26 to install on iOS 18.6.2. That means you will lose your data. Apple doesn't support downgrading iOS and this is certainly one reason why. And if you were on iOS 26 Beta, you were advised to make an Archive Backup on your computer BEFORE you installed the iOS 26 Beta. If you didn't, you made a major blunder, you can't get your data back from.

If I were you and didn't want to lose my data, I would immediately install the officially released iOS 26.

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Answer 2

WheelieNick

Level 8

45,647 points

Sep 16, 2025 01:15 PM in response to sam_6

You might want to restart your device and try to backup again to see if the issues persist

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