What causes “The last backup could not be completed” error?

[RickCMC]

I was looking at iCloud and checked my backups and noticed an error message that said “The last backup could not be completed”. That’s all it said, it didn’t give any reason why it couldn’t be completed. I have never seen that message in all the years I’ve had iPhones. I was then able to backup manually without an error. But I was wondering what causes this error in the first place?

 

[jkfrederiksen]

If you have a backup on iCloud from a beta iOS that a newer then the official. Your will get that message

 

[RickCMC]

If you have a backup on iCloud from a beta iOS that a newer then the official. Your will get that message

Hmm, I’ve never used a beta before so I have no clue why I’d get that message.

 

[jkfrederiksen]

Hmm, I’ve never used a beta before so I have no clue why I’d get that message.

Okay so I don’t know

 

[NoBoMac]

Lost wifi connection while backing up? Mid automatic backup and pulled the device off power?

 

[CTHarrryH]

I get occasionally - never quite sure why - most of my backups are manual ones that I force. I find if I get that message I just restart backup and it works fine. Never sure if it is something running on my device or network error or iCloud issue but I do get occasionally. As I said making it restart backup works for me.

 

[Minorite]

It means that backup couldn't start/was interrupted for some reason. If you can back up manually and with iTunes then everything should be OK.

 

[I7guy]

Lost wifi connection while backing up? Mid automatic backup and pulled the device off power?

In my experience, it is this issue that occurs randomly. If I want to backup I plug the phone in, make sure it's off power saving. Then go into the icloud section of settings. The navigate to your phone and press backup now.

 

[RickCMC]

Now I’m getting a message that says “Some files were unavailable during the last backup”. Any idea what this means and how to fix it? I’m

 

[spikeymike]

Now I’m getting a message that says “Some files were unavailable during the last backup”. Any idea what this means and how to fix it? I’m

Been having the same issue for the past few days now.

I've tried logging out of iCloud and back in - no luck.
Deleting old backup and starting new one - no luck.

 

[Minorite]

Now I’m getting a message that says “Some files were unavailable during the last backup”. Any idea what this means and how to fix it? I’m

You mean you get this message when trying to back up manually?

 

[RickCMC]

You mean you get this message when trying to back up manually?

I got that message after I had it plugged in and on WiFi and kicked overnight and then checked my iCloud backup. So it must have tried to back up automatically.

 

[Minorite]

And manual backup still works? If so, I would try to delete iCloud backup and do the manual one. Also if you have any VPN/Ad-Blocker running it can potentially affect iCloud backups, so check those. Also a good old reset to factory settings ususally fixes almost everything

 

[ThomasJL]

Been having the same issue for the past few days now.

I've tried logging out of iCloud and back in - no luck.
Deleting old backup and starting new one - no luck.

That's the same situation I've encountered frequently over the past few years, and it still persists in iOS 17.4.

I do manual backups, no automatic ones. It happens often with the manual backups, and it also often happened when I used to do automatic backups in the past. An error message is displayed which reads "Some files were unavailable during the last backup."