While rebooting an iPhone 7 or iPhone 7 Plus requires pressing and holding both the Sleep/Wake and Volume Down buttons for at least 10 seconds until the Apple logo appears, restarting an iPhone 8 or iPhone 8 Plus is a three step process that involves the Volume Up button, the Volume Down button, and the Side button on the device.
How to Force Restart or Hard Reset the iPhone 8 and iPhone 8 Plus
- Press and quickly release the Volume Up button.
- Press and quickly release the Volume Down button.
- Press and hold the Side button (aka power) until you see the Apple logo.
Apple made this change because on iPhone 8 and iPhone 8 Plus, pressing and holding the Side aka Sleep/Wake button and one of the Volume buttons now activates the Emergency SOS feature.
Force restarting an iPhone is different than recovery using DFU mode, for which the steps remain the same as the iPhone 7 and iPhone 7 Plus.