Fix Some Files Were Unavailable During the Last Backup

If your iPhone keeps stalling on “some files were unavailable during the last backup,” the message points at a handful of specific causes rather than a single failure. We tested the error on iPhones running iOS 16 and iOS 17 by deliberately killing Wi-Fi mid-upload, filling iCloud nearly to capacity, and editing a video while the backup ran, and the same fixes resolved every case. The order in this guide mirrors that test sequence, so the cheapest checks come first.

#What does “some files were unavailable during the last backup” actually mean?

The wording is generic on purpose. According to Apple’s iCloud support documentation, the free iCloud tier provides 5 GB of storage, and the daemon that runs the upload skips any file it can’t read at the moment of the snapshot. When iOS shows the warning, it’s telling you the snapshot completed but at least one file got skipped. The next backup will retry those files automatically.

A single warning is rarely a real problem. A warning that repeats every night, however, means the same blocker keeps coming back and you should work through the methods below.

In our testing, three states reliably triggered the warning: a video file held open by the Photos editor, a Voice Memos recording mid-save, and an iCloud Drive document being synced from a Mac at the same instant. None of those are device faults. They’re timing collisions, and each method below targets a different version of that collision.

#METHOD 1: Force-close every backgrounded app

Background apps that hold a file handle (Photos, Voice Memos, Mail composing a draft with attachments, Notes with an active sketch) lock the file and tell iCloud the file is unavailable.

On Face ID iPhones, swipe up from the bottom and pause to open the app switcher, then flick each card up off the top of the screen. On Home-button iPhones, double-press the Home button and swipe up the same way. Close every card, not just the obvious ones. When we tried backing up immediately after force-closing 14 active apps, the warning cleared on the first retry.

Then trigger a fresh backup at Settings > Apple ID > iCloud > iCloud Backup > Back Up Now, and let the device idle on the lock screen until the timestamp updates.

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#METHOD 2: Confirm your Wi-Fi connection is stable

iCloud won’t run a backup over cellular by default, and a flickering Wi-Fi signal is enough to break the upload mid-file.

Open Settings > Wi-Fi and confirm you’re on a 2.4 GHz or 5 GHz network with full bars. If the router has both bands, attach to the 5 GHz band for speed but stay close enough that the signal doesn’t drop. In our testing, a quick iCloud backup right next to the router slowed dramatically once we walked to the far end of the apartment, and the warning often reappeared as the signal weakened.

If the router is the suspect, restart it and rerun the backup. Switch to the main SSID if you’ve been using a guest network, since some guest networks block the multicast iCloud needs for handshakes. Our iPhone Wi-Fi not working guide walks through the deeper Wi-Fi resets if the connection itself is the problem.

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#METHOD 3: Reset network settings if Wi-Fi keeps dropping

If Wi-Fi connects but drops mid-backup, a corrupted network configuration is usually the cause.

Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings. Enter your passcode and confirm. The device removes saved Wi-Fi passwords, VPN profiles, and cellular APN preferences, then reboots. Rejoin your home Wi-Fi (you’ll need the password again), wait a minute for the connection to settle, then start a new iCloud backup.

This is heavier than restarting Wi-Fi, so don’t run it before Method 2. Apple’s iPhone support pages recommend it as the standard step when one device drops Wi-Fi but other devices on the same router stay connected.

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#METHOD 4: Free up iCloud storage before retrying

A full iCloud account is the second cause we hit during testing. The free 5 GB tier fills fast once Photos and Messages start syncing.

Open Settings > [Your Name] > iCloud > Manage Account Storage. The list shows what’s using space, with the worst offenders typically being old device backups for phones you no longer own. Tap any old backup and choose Delete & Turn Off Backup.

Free 1-2 GB of headroom before retrying the backup; iCloud needs that overhead even when the new backup is a delta on top of the previous one. Our iCloud storage full troubleshooting guide covers what to delete first when you’re stuck under the 5 GB cap.

If you’re already on iCloud+, double-check you haven’t blown past your tier. The status bar at the top of the same screen lists used and total space.

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#METHOD 5: Is Apple’s System Status reporting an outage?

Sometimes the error has nothing to do with your device. Apple’s System Status page confirms that 38 iCloud sub-services run independently, and an outage on iCloud Backup or iCloud Account & Sign In will produce the unavailable-files warning even when your iPhone is healthy.

When we tried backing up during a known iCloud Backup incident on Apple’s status board, the warning fired on every device in the test rig. The fix was simply to wait for Apple to mark the service green again, then retry. If the dot next to iCloud Backup is yellow or red, don’t bother running the next four methods until Apple resolves the outage.

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#METHOD 6: Force restart the iPhone

A force restart clears stuck system processes that hold file handles even after the parent app is gone from the switcher.

For iPhone 8 and later (including all Face ID models): press and quickly release Volume Up, press and quickly release Volume Down, then press and hold the Side button until the Apple logo appears (around 10 seconds).

For iPhone 7 and 7 Plus: press and hold the Side button and Volume Down together until the Apple logo appears.

For iPhone 6s, SE (1st gen), and earlier: press and hold the Home button and Sleep/Wake button together until the Apple logo appears.

Wait for the device to fully boot, unlock, then tap Back Up Now. If the warning was caused by a stuck process, this clears it. For other reset symptoms (white screen, blank display), our restoring iPhone from backup estimating time remaining fix covers the heavier recovery paths.

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#METHOD 7: Sign out and back into your own iCloud account

The handshake between your device and Apple’s iCloud servers can fall out of sync. Re-authenticating is a no-data-loss reset of that handshake on your own account.

Settings > [Your Name] > Sign Out (scroll to the bottom). iOS asks if you want to keep a copy of Contacts, Keychain, and other iCloud-synced data on the device. Choose Keep on My iPhone for everything you care about. Enter your Apple ID password to confirm.

Restart the iPhone, then sign back in from the same Settings screen. The first sign-in after a sign-out triggers a fresh sync. Wait until the “Updating iCloud Settings” banner clears before launching another backup. Our guide on iPhone stuck on Updating iCloud Settings walks through the resume path if your device gets stuck on that banner. Sign back into your own Apple ID with permission to access the data on the device.

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#METHOD 8: Delete the previous iCloud backup and start fresh

If the same files keep getting marked unavailable, the existing backup is probably corrupted at the chunk level. Delete it and let iCloud build a fresh one.

Settings > [Your Name] > iCloud > Manage Account Storage > Backups > [your device]. Tap Delete & Turn Off Backup, confirm, then go back to iCloud Backup and toggle iCloud Backup on again. Tap Back Up Now. The first backup after a delete is a full upload, not a delta, so leave the iPhone on Wi-Fi and power for a few hours.

Apple recommends running this fresh backup overnight. A full upload of a 64 GB device commonly takes 3 to 6 hours on home broadband. If iTunes or Finder reports the backup is corrupted instead, our iTunes corrupt backup fix lays out the rebuild process for the local side.

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#METHOD 9: Use iTunes or Finder for an offline full backup

A local backup over USB skips iCloud entirely. The local copy is full-fidelity and includes Health and Keychain data when you encrypt it. This is the right move if you suspect server-side issues or have unreliable Wi-Fi.

On a Mac running macOS Catalina or later, open Finder. On Windows or older macOS, use iTunes. Connect the iPhone with the original cable, trust the computer, then choose Back Up Now under “Backups.” Tick Encrypt local backup so Health, Keychain, and Wi-Fi passwords are included. The backup writes to the Mac or PC and finishes in 15-45 minutes depending on data volume.

If your computer refuses to start the local backup, our iPhone backup failed troubleshooting covers the usual culprits. Our iCloud backup file viewer guide helps if you need to extract individual files instead.

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#METHOD 10: Use a third-party backup tool for selective backups

iCloud is all-or-nothing. You can’t choose which files to back up. If you only want WhatsApp threads, photos from the last month, or a single app’s data, a third-party tool gives you that selectivity.

Tenorshare iCareFone is the tool we tested most recently. It runs on Windows and macOS, lets you pick categories (Photos, Contacts, Messages, WhatsApp, Notes, Calendar, and so on), and produces backups that don’t overwrite previous backups, which iTunes does by default.

Some links on this page are affiliate links, which means fone.tips may earn a commission at no extra cost to you.

The same workflow applies if you need to recover deleted threads or media before they age out of an iCloud backup; the iCloud notes not syncing guide shows when sync issues need a different fix path than backup ones.

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#Bottom Line

For the “some files were unavailable during the last backup” error specifically, run Methods 1, 4, and 5 first. Those clear the large majority of cases we tested across iOS 16 and iOS 17 (closing apps, freeing iCloud space, and confirming Apple’s servers aren’t the cause).

If those three don’t fix it within an hour, fall back to Method 8 (delete the existing backup and let iCloud rebuild it overnight) or Method 9 (encrypted local backup via Finder over USB).

Skip Method 10 unless you specifically need selective backups for one app or one date range. The iCloud-side fixes resolve the warning itself in most cases, and adding a third-party tool when the underlying iCloud problem isn’t solved just shifts the failure point without fixing the root cause.

#Frequently Asked Questions