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Will an iOS reinstall

  1. Work on any jailbroken-iPhone and
  2. Make a jailbroken-iPhone "unjailbroken"?
  3. Make a jailbroken-iPhone "supported by Apple"?

Similarly, does such an iOS reinstall reset the iPhone (jailbroken or not) back to a "clean, factory default" state?

My near-term purpose: I have an iPhone 4S running iOS 5.1 I'd like to jailbreak to at least install better Google Voice integration like GVIntegrated.

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    Also: what if some app/service recognizes a jailbroken iPhone as being "bad" at some point in its life, saving the "bad flag" in some database, leaving a black mark on the warranty record? Feasible? Any known app/service/mechanism that does this? (Maybe Apple wouldn't care so long as you reinstall, hence no motivation for such a thing?)
    – Johnny Utahh
    Commented Mar 26, 2012 at 23:50

5 Answers 5

Reset to default
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Apple cannot tell if you've previously been jailbroken if you do a full restore. Apple has a tutorial on how to do this (support article HT201252).

Jailbreaking only affects the software, and restoring a jailbroken device to an official version of the iOS firmware will make your device "not jailbroken." Doing a full restore can be done to any device regardless of whether or not they are currently or have previously been jailbroken.

Doing a full restore will set the device back to factory defaults for that version of iOS. A full restore erases everything including /private/var/ where all your personal data is stored. If you do an update instead of a full restore, data from the jailbreak could be left behind, since an update leaves files from the previous version.

Additional Information

There is one part of an iOS device called the NVRAM that persists even across a full restore. The NVRAM contains environment variables that are needed for the device to boot. If you have gone out of your way to make modifications to your NVRAM, it can reveal that you have been jailbroken since these modifications can only be made from a jailbroken state. If you don't know how to make modifications to your NVRAM or you've never heard of NVRAM, then don't worry, this doesn't apply to you.

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    Extremely helpful details, thx.
    – Johnny Utahh
    Commented Mar 26, 2012 at 19:46
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One word, yes.

Restoring the iPhone (in iTunes) will make it "Not jailbroken".

To avoid trouble and if you want to make sure all residual files are removed I would recommend restoring in DFU mode using the latest iOS firmware and setup the device as a new iPhone after the restore.

I had to use jailbroken iPhones for testing and this worked for me, no application ever complained that the phones are jailbroken after a full restore.

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  • Thx. You write "restoring the iPhone..." Does "restoration" involve anything other than an iOS reinstall? And can said iOS reinstall work for any jailbroken iPhone?
    – Johnny Utahh
    Commented Mar 26, 2012 at 15:03
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    Could you please and some substantial confirmation to your answer. Is this something the developers of the jailbreak say? I'd really like to believe this answer. But for now it seems insufficient ;)
    – gentmatt
    Commented Mar 26, 2012 at 15:04
  • @gentmatt It worked for me, I needed jailbroken iPhones to use on an unsupported carrier for testing. Restoring them afterwards did bring them "back" to a non jailbroken state although with a newer firmware. I don't know about any official statements from the jail breaking community, but the hardware team at my employer was positive about restoring to bring the device back to normal.
    – Coyote
    Commented Mar 26, 2012 at 15:27
  • Thx. Does anyone know if an iOS reinstall would ever fail (say because of jailbreaking or any other reason, weird scenario) on working iPhone hardware? ie, is the iOS reinstall/restore "bullet proof," similar to how an Linux/Windows/MacOS reinstall works on my any desktop/laptop (that was previously and successfully running the re-installing OS)?
    – Johnny Utahh
    Commented Mar 26, 2012 at 16:29
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    @JohnnyUtahh I don't think this is relevant to the original question, but to answer your latest question my understanding is that some unofficial firmwares modify the baseband (for SIM unlock) which then can lead to added difficulty when restoring. Restoring in DFU mode should fix the problem. If not you will have to use an alternative firmware loader in place of iTunes to force the restoration.
    – Coyote
    Commented Mar 26, 2012 at 19:41
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Fwiw. Spoke with an Apple rep at a retail, brick-and-mortar (sort of) Apple Store today. Rep said that he actually worked to confirm a customer's iPhone hardware prob by reinstalling iOS on customer's jailbroken phone, and that it was "totally cool" by him, no known (or at least strict) Apple policy against such a thing.

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Ostensibly there is no difference between a brand new phone running 5.1, and one that was jailbroken, and then restored via a full reinstall to the same OS Level. It should not leave any traces of it's history in there, so long as you set it up as a new iphone in iTunes, and do not subsequently throw a restore over the top which could reasonably be expected to hold old data etc.

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It does not only make it supported by Apple again, it will also clear possible malware out of your device which is a very good thing :)

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