iPhone erase and restore-what iOS?

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Level 2

240 points

iPhone erase and restore-what iOS?

My iPhone 4s is running iOS 8.4.1. It has had many problems of late of Apps that used to work fine, now crashing frequently and causing the phone to restart. This did not obviously correlate with an iOS upgrade. I would like to install a clean fresh version of the iOS to see if that helps, but I am confused by what happens in that process. If I erase and then restore the iPhone from a backup, am I installing a fresh copy of the iOS or the backed up version? I am guessing the backed up version because it reinstalls the old iOS version number that was present at backup and not the latest. Given that there is no way to downgrade iOS version, I am guessing that there are not available versions of older iOS. That would mean that it is potentially reinstalling a corrupted copy of the iOS, which would mean that erasing is doing no good at all. Can someone clarify?

Posted on Oct 10, 2016 5:04 AM

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Answer 1

JunhengL

Level 1

4 points

Oct 10, 2016 5:31 AM in response to David Knecht

If your iPhone is running 8.4.1 and you restore from a backup then it will still run 8.4.1.

If you update to 9.3.5 ( the latest iOS available for 4s) and restore from the backup then the iPhone will still run on 9.3.5

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Answer 2

Oct 10, 2016 5:42 AM in response to David Knecht

An iOS backup does not contain the operating system itself, so a restore from backup does not change the iOS installation at all. An iOS backup contains user and app data only - it does not contain apps themselves (they are reinstalled from the App Store or iTunes saved installers) nor iOS.

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Answer 3

David Knecht Author

Level 2

240 points

Oct 10, 2016 6:06 AM in response to Michael Black

That makes sense, but it also means that Apple has all the old iOS versions available online. But they prevent you from installing iOS7 at this point to downgrade even though, if this is correct, they could easily allow any iOS to be installed. Very annoying. My 4s crashes with many apps lately even after doing an erase and install, so something is corrupted. This did not happen immediately after installing iOS8, so I am at a loss as to what else could be causing the problem.

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Answer 4

Oct 10, 2016 8:20 AM in response to David Knecht

My understanding is that, when you do a restore, regardless of whether you restore the backup or don't, it will update the phone to the latest version of iOS that the phone will support. There is no way to restore a fresh copy of an older version of iOS.

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Answer 5

Oct 10, 2016 8:25 AM in response to IdrisSeabright

That is correct if you use the Restore iPhone button in iTunes, however, if you only click the Restore Backup it does not update iOS.

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Answer 6

Oct 10, 2016 8:31 AM in response to David Knecht

David Knecht wrote:

That makes sense, but it also means that Apple has all the old iOS versions available online.

It doesn't mean that at all. When you restore a backup it doesn't touch the version of iOS on your phone; that version remains.

While you can find any version of iOS online, Apple does prevent you from restoring any but the most recent version available for your device. It does this, most likely, because every update fixes newly identified security vulnerabilities, so if you don't always update to the latest version your phone becomes less secure over time. While Microsoft will release security updates for any recent version, and Apple will for any recent version of Mac OS, Apple does not do this for iOS. Security updates are always included in the latest release, and only in the latest release.

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Answer 7

David Knecht Author

Level 2

240 points

Oct 10, 2016 10:57 AM in response to Lawrence Finch

Just to make sure I understand what you said: If restore doesn't touch the version of iOS on your phone (I assume you mean that erase does not actually erase everything), then you have not removed the iOS and replaced it with a fresh copy, which is the goal of this exercise. If that is true, how do you wipe the iOS and replace it with a fresh copy?

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Answer 8

Oct 10, 2016 6:44 PM in response to David Knecht

In iTunes, if you specifically select to "restore from backup" then the version of iOS on the device will not be touched at all.

If you choose to "restore device" then yes, it will be erased, and it will be updated to the latest iOS version available and compatible with your hardware. You can then still restore your backup from the previous iOS version, but that will not alter iOS on the device.

If, on the device, you choose to "erase all content and settings" it will be erased but iOS will be unaltered unless you choose to update over the air or in iTunes later. Erase all content and settings does not erase iOS, just user and app data, and resets all user alterable settings back to default. You could then restore from an iCloud backup, and again, as with restore from backup in iTunes, iOS would not be touched.

There is no mechanism to install iOS without installing the latest version available and compatible with your hardware. Any erasure removes data only, not iOS. The only way to erase iOS and re-install iOS is to restore as a new device in iTunes, which will also inherently update iOS, since older versions will not be available to choose from.

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Answer 9

Oct 10, 2016 12:47 PM in response to David Knecht

The only way to replace iOS with a fresh copy is to restore the phone (not the backup) using iTunes. This will always update it to the latest version.

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