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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 Nov 19, 2015 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, 2015 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, 2015 at 20:53
  • It does make sense that the procedure is different. As of iOS15 apple has implemented the "iPhone Findable After Power Off" feature which makes the phone still send location pings even when turned off. this means the phone doesn't actually turn off completly when you "turn it off", some core or other co-processor must still be alive. Turning the phone off using the "hard reset" method should cut the power to the whole system (just as removing the battery would, as long as nothing is backed with a second battery).
    – gkpln3
    Nov 11, 2021 at 11:02

4 Answers 4

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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, 2015 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. Oct 3, 2016 at 19:39
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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.

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You might find this article by an Apple employee useful:

http://www.payetteforward.com/how-to-hard-reset-iphone-why-its-bad/

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    Welcome to Ask Different! We're trying to find the best answers and those answers will provide info as to why they're the best. Explain why you think the link you provided will answer the question. Links can change and become outdated so we prefer the answers to not just be a link. See How to Answer on how to provide a quality answer. - From Review
    – fsb
    Oct 17, 2016 at 13:41
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First-hand experience (yes, in 2021): I was facing some issues charging with MagSafe (both MagSafe Battery Pack and MagSafe Charger). Basically, the device gets hot once you charge it to 80%, and stops charging there. Tried disabling Optimized Charging but to no effect. Also, if you keep it on MagSafe at 80%, does not charge but instead slowly drains the device – which was not in use. Drops to 79, 78, 77, 76% etc. Strangely, Lightning cable charging still works.

Device restarts did not improve the situation, already on the latest version of iOS (confirmed to support MagSafe accessories). I might not have done factory reset in quite a while.

I gave it a shot going to Apple Support chat, hoping I won’t get turned down or told to do a factory reset (unlucky, this happened just after the 1-year warranty coverage ended). Basically was told to try this!! Press volume up, press volume down, hold the sleep/wake button till you see the Apple. It worked. The device immediately charged to 100% as expected, the next few days it was back to fine again.

Here’s the advice, pasted verbatim:

  1. Press and quickly release the volume up button.
  2. Press and quickly release the volume down button.
  3. Press and hold the side button until you see the Apple logo.

iOS: 15.1
iPhone 12 (i.e. the first iPhone line built for MagSafe)

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