iPhone backup starts but never finishes

Hi Jeff,

Thank you for your response.

I am using an iPhone [12] running iOS [26.2.1], and I am attempting to back up to iCloud (2TB).

For the past four months, every time I start an iCloud backup, the process begins normally but stops midway and fails before completion. It never successfully finishes. I am connected to stable Wi-Fi and the device is plugged in during the process.

Previously, my backup size was around 90 GB (as of October). Based on advice suggesting that the issue might be related to a corrupted or incomplete previous backup, I deleted my October 25 backup to start fresh.

At this moment, I have no existing backups in iCloud. However, the device is now unable to properly calculate the new backup size either — it does not complete the size estimation process.

The backup issue still persists even after deleting the old backup.

Please let me know what additional troubleshooting steps you would recommend.

Best regards,

Hilmi

Jeff, Additionally, I attempted to back up the device using the Apple Devices app on a Windows PC, and the same issue occurs there as well. The backup process starts but does not complete successfully.

Hi Jeff,

Thank you very much for the clarification and guidance.

I will free up additional storage space as you suggested and try the backup process again. Hopefully, that resolves the issue.

I really appreciate your help in advance — thank you!

Best regards,

Hilmi

Hi Jeff,

Thank you again for your suggestion.

I freed up about 20 GB of storage space on the device as you recommended and tried the backup process again. Unfortunately, the backup still stops midway and does not complete.

The behavior remains the same — it starts normally but fails before finishing. This happens both with iCloud backup and when attempting a local backup using the Apple Devices app on my Windows PC.

At this point, it seems the issue may not be related to available storage space.

Do you have any additional recommendations on what I should check next?

Thank you again for your support.

Best regards,

Hi Jeff,

Thank you again for your continued help. I followed your suggestion:

I signed out of my Apple Account/iCloud on the iPhone and chose to keep all data on the device. I restarted the phone. Then I signed back into my account and waited for everything to resync. I verified that my available storage on both the iPhone and iCloud looks sufficient, and I made sure I was connected to a strong Wi-Fi network before attempting the backup again.

Unfortunately, the result is still the same — the backup starts but stops midway and does not complete.

Please let me know what you would recommend as the next step.

I truly appreciate your patience and support.

Best regards,

Hilmi

8 GB left over 256 GB