Can I jailbreak my iPhone 4 on 4.0 firmware or do I have to upgrade to 4.0.1?


macrumors member
Original poster
Aug 8, 2010
I am using iPhone 4 with stock firmware 4.0

Can I use the method with this firmware or do I have to upgrade to 4.0.1?

I have read several problems with 4.0.1 being a bit slower, or buggy, or even draining more battery. My phone has been working fine now and don't see any reason to upgrade firmware, unless I have to do jailbreak.

So do I gotta upgrade or will I be safe at 4.0? Gotta find out before apple throws the new firmware out and screws me.

Also I plan on using the restore feature on itunes before doing the jailbreak to get a clean install. Will this restore my iPhone to 4.0 (original firmware) or will that automatically make me go to 4.0.1 firmware?


macrumors regular
Jun 1, 2010
Reno, NV
You can jailbreak on 4.0, I did it.

When you sync to itunes it will try and get you to upgrade to 4.0.1 just make sure that you don't agree to it. It will ask you to upgrade and you have to accept it if you want to. Pretty sure anyway haven't upgraded through itunes in a long time


macrumors member
Original poster
Aug 8, 2010
Did you do a fresh restore before you JB?

I don't mind doing this, but just wanna make sure the restore is gonna restore my 4.0 firmware and not try to force me into 4.0.1


macrumors 6502a
Jan 17, 2010
Evansville, In
if you do a fresh restore through iTunes you will upgrade. you need to do a restore from a backup and then you wont. but honestly just backup your phone and jailbreak and you will be fine. no need to restore first.


macrumors 65816
Sep 17, 2007
I originally jailbreak mine on 4.0, but then wanted to do the commcenter patch to enable native tethering, and had to be on 4.0.1 for that. I'm not noticing any major problems on 4.0.1 personally, and the signal bars don't seem drastically different to me. I still get full bars pretty much most places.
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