Jailbreaking iOS 4.2.1 - what you need to know

With iOS 4.2.1 being released to the masses today, here's a couple tips for jailbreakers. If you're on iOS 4.1 and jailbroken, by this point you should know how to save your SHSH blobs via TinyUmbrella or Cydia.

As of right now, most jailbreak methods that work on iOS 4.2.1 are pretty hairy. I highly suggest waiting to upgrade for the official tools, but if you feel the need to give it a try right now, I've put up an iOS 4.2.1 jailbreak guide in our forums. Ask questions, give answers, and help eachother out. You can always visit our general jailbreak forum and post other questions and find answers about other topics as well.

Whatever you decide to do, let us know how it works for you!

Update: The Dev-Team has updated their blog giving everyone a bit more information about iOS 4.2.1 and how it'll affect all devices. Make sure you read it and heed their warnings when updating. It's looking like older devices will have an easy upgrade route to a jailbreakable 4.2.1. Newer devices are (as of now) tethered. I urge anyone who wants to upgrade to weigh their options before deciding to upgrade. You may lose your jailbreak or be tethered. A tethered jailbreak basically means if your phone battery dies or you need to reboot, you'll need to be connected to a computer to enter into a jailbreak state again. They're somewhat of a pain and I'd suggest waiting for an untethered jailbreak. You probably won't be waiting long. Until then, make sure you have your 4.1 SHSH blobs saved via Cydia or TinyUmbrella!

Have something to say about this story? Leave a comment! Need help with something else? Ask in our forums!

Allyson Kazmucha

Senior editor for iMore. I can take apart an iPhone in less than 6 minutes. I also like coffee and Harry Potter more than anyone really should.

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Reader comments

Jailbreaking iOS 4.2.1 - what you need to know


Waiting for official release.
From 4.2, the thing that I really want is find my iphone... but I have some days of free trial from mobile.me, so no problem to wait. THere are some other updates that I also want, but no need to hurry. So, let's wait! :D

Always safer to wait till the DevTeam gives the thumbs up...4.2 is not a huge enough upgrade to rush anything.

Also you will lose your ability to unlock if you update. Please hold off until tools are updated.

Consider me a 27 year old jailbreaking, tethering fool. Lol. Hail the unltd data plan. 6gigs n counting this month.

@JT thats for the old baseband processor (2G,3G, old 3GS), not on new devices. At least that is what they are hinting at publicly. Newer devices have a longer wait...

@Chris + @Chris2 Yah I'm definitely a 25 year old jailbreaker...
I just downloaded Kanye West and Cradle of Filth's new albums through Safari (SafariDownloadManager)...watched a youtube clip in high wi-fi quality over 3G...and downloaded a 350MB app from the app store without having to wait until I got home to DL via wi-fi (3GUnrestrictor)...
And I love being able to reply to texts without leaving apps, or sliding to unlock, if it's locked (BiteSMS).

@p0sixninja Joshua Hill
GreenPois0n should be updated to support 4.2.1 (tethered or semitethered) within a few days.
This is worst case scenario.

Wow... Farbod, you make me feel old! :) I'm a 37 yr old jailbreaker, my husband (also JB) is 39 :) Now excuse me while I shuffle off to buy Geritol and watch Matlock. Of course, it's questionable that you young whippersnappers here would get either of those references either so... I'll just be moseying on now... :)

48 yrs and jail break in'
So I can wait on the i4
but will upgrading the iPad compromise mywi functionality?

Quick question guys: my friend's iPad is still on iOS 3.3 but he's itching to jailbreak it. Does he have to go through all of the steps in saving his SHSH before updating to the newly-release 4.2.1?

Is there anyone who can tell me how to jailbreak an iPod Touch 4g 4.2.1 step by step, thank you.