Connect to Wi-Fi and open Settings → your name → iCloud → iCloud Backup. Tap Back Up Now and stay connected until it finishes. If the backup fails, use the error on that screen to decide whether to check iCloud storage or try another Wi-Fi network.
01The iPhone says there’s not enough iCloud storage
Section linkGo to Settings → your name → iCloud and check how much space is available. Tap Storage or Manage Account Storage → Backups → this iPhone. Wait for Next Backup Size to appear and compare it with the free space in iCloud. If the backup needs more room, review what you can safely remove or increase your iCloud storage. Keep any backup copies you still need.
02The last backup failed or the upload is slow
Section linkIf the backup ends with an error despite enough space, try another trusted Wi-Fi network and check for an iOS update under Settings → General → Software Update. If the upload is still in progress, check the network’s upload speed. Apple suggests leaving the iPhone on power and Wi-Fi for 24 hours when a backup takes longer than expected. If it still hasn’t finished, archive your important data separately before trying again.
03iCloud Backup is greyed out
Section linkCheck the iCloud Backup screen for a restore in progress. Wait for the restore to finish before trying a new backup. On a work or school phone, look under Settings → General → VPN & Device Management for a management profile and ask the administrator whether backup is restricted.
04Make sure a fresh backup exists
Section linkReturn to the iCloud Backup screen and look at the date and time below Back Up Now. Check that it matches the backup you just ran. For automatic backups, turn on Back Up This iPhone and leave the phone plugged in, connected to Wi-Fi, and locked.