Jailbreak iOS 4.2.1 Untethered On iPhone 4 Without Updating Baseband Via TinyUmbrella [Guide]

It’s been a busy day for jailbreakers since Chronic Dev-Team has released greenpois0n RC5 which jailbreaks your iPhone 4/3GS, iPod touch or iPad on iOS 4.2.1 completely untethered and we recently published a step-by-step guide on how to do it. However, that is only suitable for those who do not rely on a software unlock (ultrasn0w) for using their iPhone on an unsupported carrier. Now until a pwnage tool comes out for this, folks at FSM have posted a nice and quick guide for iPhone 4 users to jailbreak on iOS 4.2.1without updating their baseband and preserving ultrasn0w unlock.

Before you proceed, please note:

  • This procedure is for iPhone 4 ONLY!
  • Make sure your iPhone 4’s current baseband (e.g 1.59.00) is supported by ultrasn0w 1.2. (you can check the list of supported basebands here)

Step 1:

Download and install TinyUmbrella from here .

Step 2:

Download the official iOS 4.2.1 firmware for iPhone 4 here.

Step 3:

Load TinyUmbrella and Start TSS Server. To make sure it’s running, check out the logs…

Jailbreak iOS 4.2.1 Untethered On iPhone 4 Without Updating Baseband Via TinyUmbrella [Guide]

Step 4:

Start iTunes

Step 5:

Now Plug-in your iPhone 4.

Step 6:

Restore to official iOS 4.2.1 using the downloaded firmware

Step 7:

You will get an Error 1013. That’s totally normal.

Step 8:

Put your iPhone 4 in DFU mode and jailbreak it untethered using greenpois0n RC5 by following this step-by-step guide.



  • Fixing issues with greenpois0n RC5 Untethered Jailbreak for iOS 4.2.1.
  • How To Unlock iOS 4.2.1 On iPhone 3GS / 3G With Baseband Update To 06.15.00 Using PwnageTool 4.1.3 + Ultrasn0w 1.2 [Guide]

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I'm a technology enthusiast specializing in Diagnostic Radiology. I'm crazy about Formula 1, all sorts of gadgets, surfing, console gaming, movies, music & I simply LOVE high-end designer wear! Follow me on Twitter @DrUsmanQ