Why does iOS 15 say error?

iOS 15 is the latest major release of Apple’s iOS operating system for iPhone and iPad devices. Since its public release in September 2021, some users have encountered errors when trying to install or use iOS 15. There are a few common reasons why users may see errors on iOS 15:

Incompatible or Older Device

iOS 15 only supports iPhone and iPad models going back to the iPhone 6s and iPad Air 2 released in 2015. Trying to install iOS 15 on an older iPhone or iPad that is not supported will result in an error message. Apple provides a list of compatible devices on their iOS 15 preview page. If your device is older than the iPhone 6s or iPad Air 2, you will need to stay on your current iOS version and will be unable to upgrade to iOS 15.

Insufficient Storage Space

Updating to iOS 15 requires at least 12GB of available storage space on an iPhone or iPad. If you have photos, videos, or apps taking up most of your device’s storage, you may encounter errors trying to install iOS 15 due to insufficient storage. You can check your current available storage in Settings > General > iPhone/iPad Storage. Deleting unused apps, messages, and media can free up space to meet the minimum 12GB requirement.

Connection Issues

In order to install iOS 15, your iPhone or iPad will need to be connected to the internet via WiFi or cellular data. Connection errors may prevent the update from downloading or completing properly. Make sure you are connected to a stable, high-speed internet connection when installing major updates like iOS 15. If you are still getting connection errors, try resetting your network settings or updating using a computer with iTunes or Finder.

Beta Software Installed

If you previously installed the iOS 15 beta software on your device, you may encounter errors trying to update to the public release. Any beta software needs to be removed before installing the official iOS 15 release. You can remove the beta profile under Settings > General > VPN & Device Management. Your device will then need to be erased and set up as new before installing iOS 15.

Other Software Errors

Sometimes errors during or after an iOS 15 install may indicate a different software issue. For example, errors with “Slide to Upgrade” or “Verification Failed” often mean there was a problem verifying the iOS 15 update package. A message about being “Unable to Install Update” usually indicates issues connecting to Apple’s servers. These types of errors typically require fixing with a computer and iTunes/Finder.

Common iOS 15 Error Messages and Fixes

Here are some of the most common error messages users may see when trying to install or use iOS 15:

“Software Update Failed”

This generic error message appears when the iOS 15 installation encountered an unspecified problem. Some potential fixes include:

– Check for and install any iOS 15 updates in Settings that may fix the issue.
– Make sure your device has enough storage space and a stable WiFi or cellular data connection.
– If updating wirelessly, try updating to iOS 15 using a computer instead.

“iPhone could not be updated. An unknown error occurred (4013)”

Error 4013 indicates an issue communicating with the update servers. Solutions include:

– Update your device using a computer with iTunes or Finder instead of wireless.
– Verify your internet connection is working correctly.
– Try changing your DNS servers to Google or Cloudflare DNS.
– As a last resort, restore your device using a computer.

“Unable to Verify Update”

This verification error is typically fixed by:

– Updating your device with a computer and iTunes/Finder using recovery mode.
– Make sure you have the latest version of iTunes or Finder on the computer.
– Check that the date and time are set correctly on your device.

“iPhone could not be restored. An unknown error occurred (4013)”

Error 4013 when restoring an iPhone or iPad in recovery mode is often resolved by:

– Force restart your device and try restoring again in recovery mode.
– Use a different Lightning or USB cable between the device and computer.
– Try a different computer and latest iTunes/Finder if possible.
– As a last resort, contact Apple Support for further troubleshooting.

“Not enough storage available”

As mentioned earlier, iOS 15 requires at least 12GB of available storage space. To free up space:

– Offload unused apps
– Delete messages, emails, and photos/videos
– Transfer photos to a computer or cloud storage
– Disable iCloud backups temporarily
– Delete music, books, or podcasts you don’t need

Fixing iOS 15 Installation Problems on iPhone/iPad

If you run into errors trying to install iOS 15 wirelessly on your iPhone or iPad, the best solution is often to update using a computer with iTunes (on Windows) or Finder (on Mac). Here is a general process for fixing iOS 15 install errors with a computer:

1. Download and install the latest version of iTunes (PC) or macOS Finder (Mac).

2. Connect your iPhone or iPad to the computer using the USB cable.

3. Force restart your device: Press and quickly release the Volume Up button, press and quickly release the Volume Down button, then press and hold the Side button until you see the recovery mode screen.

4. Open iTunes/Finder. It should recognize your device in Recovery Mode and prompt you to Restore.

5. Click Restore and wait for the iOS 15 installation to complete. Your device will restart normally once finished.

6. If you backed up your device to iCloud or iTunes before, you can then restore from that backup during the device setup process to retain your data and settings.

This recovery mode restore process using a computer often resolves many types of iOS 15 installation errors. It essentially re-installs a clean, up-to-date version of iOS 15 along with any device firmware that needs updating. If you continue to get errors restoring iOS 15 in recovery mode, you may need to schedule a Genius Bar appointment at an Apple Store for additional troubleshooting.

How to Fix Common iOS 15 Problems

Aside from installation errors, some users also reported problems after updating to iOS 15 such as:

  • Decreased battery life
  • Apps crashing or freezing
  • Touch screen not responsive
  • Can’t sign in to iCloud
  • Keyboard lag or unresponsive
  • Overheating iPhone

Here are some steps to fix the most common iOS 15 problems after updating:

Restart and Reset Device

Oftentimes, simple restarting your iPhone or iPad can clear up minor system glitches after an iOS 15 update. For a deeper reset, go to Settings > General > Reset and choose Reset All Settings to fix issues like freezing apps, touch screen problems, or iCloud sign-in errors without erasing your data.

Check for iOS Updates

Apple will push bug fix updates to address issues with a major iOS release, so always install the latest iOS version via Settings > General > Software Update. iOS 15.0.1, iOS 15.0.2, iOS 15.1 etc contain many fixes for problems encountered on iOS 15.

Disable Certain Features

Some new iOS 15 features like SharePlay or Live Text use camera, internet, and processing resources in the background which could impact battery life and app performance. Try disabling problem features under Settings to see if that helps.

Erase and Restore iPhone

For serious system problems, it may be best to completely erase your device and setup as new, rather than restoring a backup. This will purge any corrupted files or settings left over from the iOS 15 upgrade. Re-download your apps and only transfer necessary data back afterwards.

Remove Beta

If you installed the iOS 15 beta prior to the public release, any leftover beta software could cause conflicts. Remove the beta profile under Settings > General > VPN & Device Management.

Contact Apple Support

For software bugs persisting through multiple iOS 15 updates, you will likely need to contact Apple Support directly for troubleshooting. They can run diagnostics and possibly recommend a warranty service for any device hardware issues uncovered.

How to Downgrade from iOS 15 to iOS 14

If iOS 15 is causing severe problems on your iPhone and you want to go back to iOS 14, there are a few steps involved:

1. Back up your iPhone data first via iCloud or iTunes on your computer. All device data will be deleted when downgrading.

2. Download the iOS 14 IPSW file for your specific iPhone model from ipsw.me. This contains the full system image for iOS 14.

3. Connect your iPhone to your computer and open Finder or iTunes.

4. While holding the Option key on Mac or Shift key on Windows, click Restore iPhone. Select the iOS 14 IPSW file you downloaded.

5. Once the downgrade is complete, you can then restore your data and settings from the backup you made.

Downgrading from iOS 15 to 14 causes a full erase of your device’s data, so it should only be done as a last resort if you are experiencing major issues. Not all devices can be rolled back to iOS 14, so check compatibility before attempting a downgrade.

iOS 15 Tips and Tricks

While iOS 15 has had some launch issues for certain users, overall it brings many great new features once installed and running smoothly. Here are some helpful tips to take advantage of what’s new:

Focus Mode

The new Focus feature lets you set different notification and home screen profiles for work, sleep, fitness, gaming, and more. You can automatically filter apps and people based on a specific Focus.

Live Text

iOS 15 adds the ability to select, copy, lookup, and translate text right within photos or live camera previews. It uses on-device intelligence to detect text.

Maps Upgrades

Apple Maps gets a major update in iOS 15, with much greater detail for roads, buildings, elevation, and landmarks in supported cities. There’s also AR walking directions and new ways to explore cities.

Wallet and Keys

Wallet can now store ID cards like drivers licenses, which users in participating states can add via the app. There’s also support for home keys, hotel keys, office keys, and car keys in Wallet using NFC.


SharePlay lets you have a synced experience with other users across FaceTime. You can listen to music, watch TV/movies, share your screen, and use apps together with friends.

Safari Redesign

iOS 15 brings a new streamlined tab bar to Safari for one-handed use, plus tab groups for organizing all your open tabs. The address bar also moves to the bottom for easy access.


While iOS 15 has brought issues for some users like various error messages and bugs, there are lots of troubleshooting steps like updating with a computer, downgrading to iOS 14, or contacting Apple Support that should resolve most problems. Make sure to keep your device data backed up before any major troubleshooting. When iOS 15 is running smoothly, the upgrades like Focus mode, Live Text, Maps improvements, Wallet updates, SharePlay, and the new Safari redesign provide great new iPhone and iPad functionality.

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