iPhone 13 Keeps Rebooting on Its Own? Here’s How to Fix It (iOS 15.2.1)

If your iPhone 13 is randomly shutting down and restarting without warning, it’s not just annoying—it can make your phone practically unusable. Fortunately, this is often a software issue that you can fix without going to Apple Support. Below are all the most effective fixes you can try if your iPhone keeps rebooting unexpectedly on iOS 15.2.1.

1. Install Pending iOS and App Updates

Apple and app developers frequently release updates to fix bugs—including reboot issues.

Update iOS:

Go to Settings > General > Software Update
If an update is available, tap Download and Install

Update Apps:

Open the App Store
Tap your profile icon at the top right
Tap Update All

After updating, restart your iPhone to make sure all changes are properly applied.

2. Offload Unused Apps

Freeing up storage can help if your phone is low on memory, which might be causing instability.

Enable automatic offloading:

Go to Settings > App Store
Toggle Offload Unused Apps ON

Manually offload problematic apps:

Go to Settings > General > iPhone Storage
Tap the app causing issues
Select Offload App

3. Optimize iPhone Storage

When your iPhone has less than 2GB of free space, it may start to behave erratically.

Check storage:

Go to Settings > General > iPhone Storage
Delete unused apps, large videos, and old messages

You can also move photos and files to iCloud or an external backup.

4. Reset All Settings

If you recently changed some settings or installed something that might’ve conflicted with your system, resetting all settings might help.

To reset all settings:

Go to Settings > General > Transfer or Reset iPhone
Tap Reset > Reset All Settings
Enter your passcode and confirm

This will reset system preferences like Wi-Fi and Display settings, but it won’t delete your data.

5. Perform a Factory Reset

If none of the above work, you may need to erase everything and start fresh.

Before you begin:

Back up your data via iCloud or iTunes

To factory reset:

Go to Settings > General > Transfer or Reset iPhone
Tap Erase All Content and Settings
Follow the prompts to fully wipe your phone and reinstall iOS

Set it up as new initially to check if the problem returns. If stable, you can then restore your backup.

6. Restore via iTunes or Finder

If your phone crashes mid-reset or during use, restore it through a computer for a safer, more stable process.

Connect iPhone to your computer via Lightning cable.
Open iTunes (Windows/macOS Mojave or earlier) or Finder (macOS Catalina or later).
Select your device and click Restore iPhone.

Follow the instructions to either restore from backup or set up as new.

7. Recovery Mode or DFU Restore

Still having issues? These advanced restore methods can help fix deep software corruption.

Recovery Mode Restore:

Enter recovery mode by pressing:
1. Volume Up (quick press)
2. Volume Down (quick press)
3. Hold the Side button until the recovery screen appears
In iTunes/Finder, choose Restore

DFU Mode Restore:

DFU (Device Firmware Update) goes even deeper than recovery mode
Use only if the issue persists after recovery mode
(Let me know if you want step-by-step DFU instructions.)

Both options will erase everything, so back up first if possible.

8. Try Third-Party iOS Repair Tools

Some tools can repair iOS without erasing your data:

Popular options:

ReiBoot by Tenorshare
Dr.Fone – Repair
PhoneRescue for iOS
AnyFix by iMobie

Use them with caution, and always choose a reputable source.

9. Suspect Hardware? Time to Visit Apple Support

If you’ve tried everything and your iPhone 13 is still rebooting randomly, the issue may be hardware-related—possibly involving the battery, logic board, or other internal components.

Visit the nearest Apple Store or an authorized service provider
Check your warranty or AppleCare+ status—you may be eligible for a replacement or free repair