iPhone keeps restarting? 9 fixes that actually work
Random restarts usually come from a buggy update, an app, a worn battery or a bad SIM card. Start with the fixes that take seconds, then narrow it down.
There are two different problems people describe the same way. In a restart loop, the phone never finishes starting up and shows the Apple logo again and again. With random restarts, the phone works normally, then suddenly goes black and restarts every few minutes or hours. The fixes overlap, but if your phone never gets past the logo, jump to our guide for an iPhone stuck on the Apple logo.
Find the cause first: check the panic log
When iOS crashes hard enough to restart, it saves a report called a panic log. It takes a minute to check and it often points straight at the culprit.
- 1
Open Settings › Privacy & Security.
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Scroll down and tap Analytics & Improvements, then Analytics Data.
- 3
Look for files that start with “panic-full” and today’s date.
If there are none, the restarts are probably not system crashes. Focus on apps and the battery.
- 4
Open the newest one and look near the top for a line with “Missing sensor(s)” or “userspace watchdog timeout”.
A missing sensor usually points to hardware, such as a damaged charging port cable or battery. A watchdog timeout usually points to software.
How to stop an iPhone from restarting
The fix
Work through these in order
- 1
Force restart the iPhone.
Press and release volume up, press and release volume down, then press and hold the side button until the Apple logo appears. This works on iPhone 8 and later and clears most temporary glitches.
- 2
Update iOS.
Go to Settings › General › Software Update. Apple often fixes restart bugs in small updates released a week or two after a major release.
- 3
Update every app.
Open the App Store, tap your profile picture and tap Update All. An outdated app can crash the system after an iOS update.
- 4
Remove any app you installed just before the restarts started.
If the problem began right after installing something, delete it and see if the restarts stop.
- 5
Free up storage.
An almost full iPhone can become unstable. Check Settings › General › iPhone Storage and aim for at least a few gigabytes free. Our guide to clearing space without deleting photos walks through the quickest wins.
- 6
Take the SIM card out as a test.
A faulty SIM or a carrier settings problem can cause restarts. Remove the physical SIM with the tray tool and use the phone on Wi-Fi for a while. If the restarts stop, ask your carrier for a new SIM.
- 7
Check battery health.
Go to Settings › Battery › Battery Health & Charging. If Maximum Capacity is below 80% or you see a Service message, a battery replacement is the likely fix.
- 8
Reset all settings.
Go to Settings › General › Transfer or Reset iPhone › Reset › Reset All Settings. This keeps your photos and apps but resets Wi-Fi passwords, wallpaper and privacy settings to default.
- 9
Update or restore with a computer.
If the phone restarts too often to use, connect it to a Mac (Finder) or a Windows PC (Apple Devices app), put it in recovery mode and choose Update. Only choose Restore if Update fails and you have a backup, because Restore erases the phone.
Why does my iPhone restart when it gets cold or at low battery?
That pattern points to the battery. A worn battery struggles to deliver power in cold weather or when it is nearly empty, and the phone shuts down or restarts to protect itself. A replacement usually solves it completely.
Frequently asked questions
Why does my iPhone restart by itself?
The most common causes are a software bug after an update, an app that crashes the system, a worn battery that cannot supply enough power, a faulty SIM card, or a hardware fault such as a damaged charging port.
Will a force restart delete anything?
No. A force restart only switches the phone off and back on. Your photos, messages and apps stay exactly where they are.
Can a bad battery make an iPhone restart?
Yes. A worn battery can drop its voltage suddenly under load, and the iPhone restarts to protect itself. Check Settings › Battery › Battery Health & Charging. Below 80% makes this more likely.
What to try next
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