You are texting, sending an Email or in the middle of Pokémon GO , all of a sudden, your iPhone 4/4s/5//5c/5s/6s/6s Plus shut off and restart. What a bummer! Even worse, the problem keeps happening. That's it, the terrible headache that has troubled thousands of iPhone users.
Unfortunately, no one knows exactly why your iPhone keeps restarting, including Apple itself. Other than suggesting a new iPhone, here we gather solutions that has been proved effective by other users, hopefully they could be the remedies for this terrible headache.
Remedy 1: Delete Troublesome Apps
If your iPhone starts rebooting cycle after you installed some new apps, maybe these apps are the problem. Therefore, delete the apps from your iPhone: on iPhone home screen, tap and hold the app's icon until you see the small "x" on the upper corner of the app, tap the "x" and choose deleting the app and its data. After deleting, reboot your iPhone by pressing and holding the Power button. Then sync your phone to iTunes.
Tip: Sometimes when syncing with iTunes, you'll find the app that you have deleted reappeared on your iPhone. Therefore, before syncing with iTunes, go to iTunes, choose "Apps," if the app is on the list, click the small "x" on the app icon to delete it.
Remedy 2 Turn Cellular On/Off
Some users reported that they have fixed the problem by turning on/off the cellular. we can't guarantee it will also work for you, but it worth trying since it is such an easy method. Before you go deeper, if the cellular data is on, just turning the cellular on/off and see how it works.
Remedy 3: Reset All Settings
Go to Settings>General>Reset >Reset All Settings.
Remedy 4: Restore from An Old Backup
If the above methods fail, try to fix the restarting problem by restoring your iPhone from an old backup on iTunes. Connect your iPhone to iTunes, select Restore Backup, choose an old backup and click Restore. Then wait patiently for the restoring to complete. Your device will restart.
Remedy 5: Perform a Hard Reset
If your iPhone continues to restart after the above steps, then perform a hard reset to fix the problem. To force restart your device, press and hold both the Sleep/Wake and Home buttons for at least ten seconds, until you see the Apple logo.
Remedy 6: The DFU Reboot
The method has find effective by many users, but remember: you'll lose all data on your iPhone because it is a complete restore of the iPhone.
Connect the iPhone to computer, then power off the iPhone.
After iPhone is off, hold the Power and Home buttons at the same time for about 10 seconds.
Then release the Power button, but keep holding the Home button until you see an iTunes message saying "iTunes has detected an iPhone in recovery mode".
Release the Home button, your iPhone screen will be all black. This means the iPhone has entered DFU mode.
Restore your iPhone using iTunes.
Remedy 7: Replace iPhone Battery
Sometimes it is battery that causes rebooting problem. Replace your iPhone battery with a new one, this could be helpful.
You probably have noticed that the methods mentioned above will delete data on your iPhone, such as Remedy 4, Remedy 5, Remedy 6. So it will be good idea that you have backed up your iPhone data before fixing the restarting problem. You can back up your iPhone data with iCloud, iTunes or FonePaw iOS Transfer.