Backup: iPhone or iPad backup never finishes

If your backup stalls, restarts on its own, or displays an error at a specific percentage, several factors may be causing the issue. This guide identifies the most common causes and links to detailed solutions in our dedicated guide on Understanding and fixing slow iPhone or iPad backups.

Check your connection

If backing up over Wi-Fi, try switching to USB. If already on USB, try a different port and connect directly to your computer rather than through a hub or dock. Cable quality also matters — for iPhone 15 and later, use a USB-C cable that supports USB 3.0 or higher for faster transfers.

For full guidance on connection types, cable recommendations, and Wi-Fi requirements, see Device-to-computer connection considerations.

Check your backup location

Backing up to a network drive or NAS takes significantly longer than backing up to a local or external drive. If your backup to a network drive is not finishing, try connecting the drive directly to your computer via USB or Ethernet for the first backup, and pause other backup software (such as Time Machine on macOS) while iMazing is running.

For recommendations on external drives, NAS configuration, and locations to avoid, see Backup location considerations.

Check available space

If your device has less than 5-7% free storage, the backup will run significantly slower and may fail to complete. Free up space on your device, then retry the backup.

For details on checking and managing storage on both your device and your backup destination, see Available space.

Prevent file modifications during backup

iOS restarts the backup process whenever a file changes mid-backup. To prevent this, enable Airplane Mode on your device before starting the backup, and avoid using the device until it finishes.

For more on why this happens and how to manage it, see Files modified on device during the backup process.

Check third-party software

Antivirus, firewall, VPN, and sync software (Dropbox, Google Photos) can interrupt or slow down backups. Quit or pause these applications before starting a backup, and exclude your backup location from antivirus scanning.

For a full list of known conflicts and how to resolve them, see Third-party software and security solutions.