Apple always prompts the reason for the backup failure.

Apple always reminds me of backup failure. Let's have a look.

Apple's backup failed, probably because iCloud was out of space. In the case of free, iCloud only has 5GB of space.

In addition, if the reminder of iCloud backup failure keeps appearing after backup is turned off, you can upgrade the size of iCloud storage space and perform normal backup.

Or check the size of the next backup, then empty the iCloud storage space (to remind you to do offline backup), leave enough backup space for the next size, and then make a normal backup. After the backup is successful, close iCloud backup again, and there will be no more reminders.

When the last backup failed, even if the backup was closed, a failure reminder would still appear. This backup reminder is a reminder that the last backup was unsuccessful, so it will still appear even if all backups are closed.