iPhone or iPad won't back up to iCloud

• 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 might take a few minutes for your device to calculate Next Backup Size.
• If your backup needs more space than the amount you have 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

iPhone: Settings → [your name] → iCloud → iCloud Backup iPad: Settings → [your name] → iCloud → iCloud Backup

Apple: If you can't back up to iCloud ↗

• Open the Settings app, then tap Wi-Fi to make sure that you're connected to Wi-Fi.

Apple: If you can't back up to iCloud ↗

• Open the Settings app, tap General, then tap Software Update. Download and install any available updates for your device.

iPhone: Settings → General → Software Update → Automatic Updates iPad: Settings → General → Software Update → Automatic Updates

Apple: If you can't back up to iCloud ↗

• Try to back up on another Wi-Fi network.

Apple: If you can't back up to iCloud ↗

• Check your upload speed.
• Leave your device connected to power and Wi-Fi for 24 hours. If your backup still isn't done, archive important data, then try these steps again.

Apple: If you can't back up to iCloud ↗

• 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 see “This [device] is currently being restored and will automatically back up when it is done.” You can create a new backup after your device finishes restoring.
• Check whether you 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.

Apple: If you can't back up to iCloud ↗