If you can't back up to iCloud
Find out what to do if you need help backing up your iPhone or iPad with iCloud Backup.
If an alert says that there's not enough iCloud storage
Open the Settings app, then tap your name.
Tap iCloud. At the top, you can check how much iCloud storage you’ve used.
Tap Storage or Manage Account Storage.
Tap Backups, then tap the device you're using. Next Backup Size should show you the size of the next backup. It may take a few minutes for your device to calculate Next Backup Size.
If your backup needs more space than the amount of space that's available in iCloud, you can:
Delete information that you don’t need to reduce the size of your backup
Upgrade your iCloud+ plan to get more space
If a message says that your last backup couldn't be completed
Open the Settings app, then tap Wi-Fi to make sure you’re connected to Wi-Fi.
Open the Settings app, tap General then tap Software Update. Download and install any available updates for your device.
Try to back up on another Wi-Fi network.
If your iCloud backup is taking longer than expected to finish
Open the Settings app, then tap Wi-Fi to make sure you’re connected to Wi-Fi.
Check your upload speed.
Leave your device plugged in to a power source and connected to Wi-Fi for 24 hours. If your backup still isn’t done, archive important data, then try these steps again.
If the iCloud Backup option is greyed out
Check if a restore is still in progress. Open the Settings app, tap your name, tap iCloud then tap iCloud Backup. If your device is still being restored, you will see a message stating "This [device] is currently being restored and will automatically back up when it is done". You can create a new backup after your device has finished restoring.
Check whether you've installed a profile that restricts iCloud Backup. Open the Settings app, tap General then tap VPN & Device Management to see a list of installed profiles.
If you need help restoring from an iCloud backup
Find out what to do if you receive an error while restoring from an iCloud backup, if you don’t see the backup you want to restore and more.
Find out what to do if restore from iCloud backup failed