I'm presenting a talk on troubleshooting OS X and iOS for a Mac user group next month, and I was surprised to hear that several members thought a "hard reset" or force restart of an iPhone or iPad is a useful troubleshooting procedure. They suggested that it does some sort of clearing of caches or resetting of [insert hand waving here] which is different from simply shutting the device off and turning it back on.

I've searched pretty deeply across Apple's support site, the Apple discussion forums, the popular Apple news websites, and sites offering Apple tech tips and I haven't found any corroboration.

To clarify the answer I'm seeking, I'm particularly looking for firsthand knowledge (i.e. "Apple told me a force restart does foo") or a published reference that confirms one way or the other.

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    I know I've had Apple techs ask me to do this AFTER a soft restart, though it never resolved any problems for me a soft restart didn't, so at a minimum it's non-harmful – agentroadkill Nov 19 '15 at 15:36
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    @agentroadkill It is dangerous to not let apps and the system close files, save state before shutting down. Yes, lots of checks are built in to correct system corruption that creeps in when you do this, but nothing will fix corrupt photos or other data files when you harm them by pulling the plug on a running OS. The odds of harm here aren't as bad as spinning the barrel and pulling the trigger on a gun with one bullet, but saying you dodged an issue doesn't make this non-harmful in the general sense. – bmike Nov 19 '15 at 16:34
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    There was a time (iOS 4) when a hard reset did do something. Many iPhone 3 users, including me, had significant performance problems after the iOS 4.0 upgrade and a hard reset really did make a huge improvement (I can attest to this). However I don't know exactly what the hard reset did or if this behavior persists in the latest iOS version (9). Based on the answers so far, it seems not. – Keith Nov 19 '15 at 20:53

A force restart is at the hardware level, not the software level. This means that even if iOS is completely frozen or in a different mode altogether (such as DFU Mode, Recovery Mode, or Restore Mode), you can still perform a force restart. It does nothing more than cut the power and turn the device back on again. This means that it doesn't clear any caches or reset anything. A regular restart actually does more than a force restart.

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    This is exactly what I assume happens. It's certainly possible that iOS notices on startup that it was shutdown unexpectedly and runs some additional procedures. My guess is that it doesn't do anything it wouldn't do on a normal boot, but I'd love some stronger confirmation either way. – Adam Rice Nov 20 '15 at 16:19
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    @AdamRice If I ever find any information that says otherwise, I will update my answer, but in all of my research, I haven't found anything. – Andrew Larsson Oct 3 '16 at 19:39

The "Hard Reset" is a useful troubleshooting feature, because it's very often the only way to restart an iOS device that's malfunctioning. Normally it isn't advisable to do it for the same reason as on a Mac: it may cause corruption. But it's definitely a useful thing to know how to do for the times you need it. It actually does less than a regular restart, because it prevents the OS from following normal shutdown procedures. Not a great thing to do on a regular basis and there are better ways to force a filesystem check of the device without potentially causing data files to be left in an inconsistent state.


You might find this article by an Apple employee useful:


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