iPhone boot loops and cannot be restored with iTunes

My friend gave me an iPhone and told me if I could fix it, I could keep it. I plug it in, and it bootloops, but I am able to get it into DFU mode/Recovery mode. I try to restore it with a Mac, but only get an "Error 21" message. When I try restoring, the device boot loops until it eventually goes back to the recovery mode screen, and I get the error message.

Earlier iPhone models

Posted on May 24, 2024 6:04 AM

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3 replies

May 24, 2024 6:25 AM in response to penn177

Here are some common solutions you can attempt:


  1. Follow the Apple article to resolve the issue --> If your iPhone, iPad, or iPod touch won't turn on or is frozen ...
  2. If not resolved; please follow the steps in the following link for support with this issue: If your iOS device restarts or displays the Apple logo or a spinning gear unexpectedly
  3. Sometimes, a simple restart can resolve temporary software glitches. Turn off your iPhone, wait for a few seconds, and then turn it back on.
    1. Restart the device. That's it.
    2. Still not solved --> Force restart iPhone - Apple Support
  4. Make sure you have the latest updates installed. Update using iTunes/Finder —> Update your iPhone, iPad, or iPod touch - Apple Support (IN)
  5. You still see a black screen after charging, force restarting, following the steps in this article.
    1. You see a black screen, but you can hear alerts, sounds, and vibrations.
    2. The screen remains black, but the device chirps when you unmute it and connect it to power.
    3. Your screen is on, but it doesn't respond when you tap, slide, or try other gestures. 
    4. You can't force your device to restart because a button is broken or stuck.
    5. Your device is stuck on the Apple logo, displays a solid color, or isn't recognized in iTunes.
    6. Contact Apple Support to set up service if you have any of the above issues:
  6. Please follow the steps in the following Apple Video for support with this issue:



If none of the above steps resolve the issue, it is recommended to reach out to Apple Support or visit an authorized service center for further assistance. They can provide specific guidance based on your device model and iOS version.



May 24, 2024 6:26 AM in response to penn177

See this --> If you see an error when you update or restore your iPhone, iPad or iPod - Apple Support (IN)


Or this --> iOS update and restore errors - Apple Support


Error 53 --> If you see error 53 when you update or restore your iPhone or ...


Error 9, 4005, 4013, 4014 --> If you see error 9, 4005, 4013, or 4014 when you restore your ...


Try updating iOS after each step.

  • Try to Forget the WiFi network and add it again
  • Try another WiFi network 
  • Toggle sets automatically off and then on
  • Reset your network settings
  • Force restart your device
  • Remove any beta profiles, if applicable





VPN or proxy connections might prevent your device from contacting the update servers.



Here are some things you can try:


Basic checks:

  • Make sure your iPhone is connected to a stable Wi-Fi network. A weak or intermittent connection can cause update issues.
  • Ensure your iPhone has enough storage space. The update might not be able to download if your storage is full. Go to Settings > General > [Device name] Storage and see how much space you have available. If you need to free up space, delete unnecessary apps or files.
  • Force restart your iPhone. This can clear any temporary glitches that might be causing the problem. For an iPhone 7, press and hold the Sleep/Wake button and the Volume Down button simultaneously until you see the Apple logo.
  • Sometimes, a simple restart can resolve temporary software glitches. Turn off your iPhone, wait for a few seconds, and then turn it back on.
    1. Restart the device. That's it.
    2. Still not solved --> Force restart iPhone - Apple Support



More advanced troubleshooting:




iPhone boot loops and cannot be restored with iTunes

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