Downgrade iOS 4.2.1 on iPhone and iPod Touch

Apple recently released iOS 4.2.1 which added quite a few awesome features including AirPlay, AirPrint, Safari “find on page”, and free “Find your iPhone” feature for iPhone 4. (sorry 3GS and 3G users… Apple purposely wrote you guys out of the deal.) My personal favorite would have to be the Safari search feature. I have no idea why Apple didn’t include this simple feature in the year before…

HOWEVER… along with new features iOS 4.2.1 brought us more woes than ever before as well.

  1. Battery drains EXTREMELY quickly with this release. I would have nothing running in the background of my iPhone 4… and the phone will get warm. It almost feel like the phone is constantly accessing something… and it just drains the battery right out.
  2. Jailbreak is still tethered! This means you have to physically attach your phone to your computer every single time you reboot. so imagine putting your phone into DFU mode and uploading the jailbreak exploit every single time. Not fun!
  3. Cydia and other jailbroken apps still cannot work well with iOS 4.2.1 yet. Although Cydia has been updated to run on iOS 4.2.1 it is still not very stable from what I could tell.

So to sum up… after having iOS 4.2.1 running for 4 days (3 days unjailbroken, 1 day jailbroken) I finally decided to revert back to 4.1
Also, the heating/battery issue was worse after jailbreaking… I tested repeatedly and found this to be true.

So here is how to downgrade your iOS 4.2.1 device to iOS 4.1 or earlier.

Before we begin, you will need

There are guides out  there like this one, but none of those worked for me. Every time I tried to restore to 4.1 iTunes spits back an error 1600 or 200… and won’t continue.
Here is how I made it work for my iPhone 4.

  1. Point to the Cydia clone.
    • Open your host file, and add
    • This will fool iTunes to recognize your SHSH saved on Cydia. However, this step is not need for iPhone 3G and iPod Touch 2G (MC version) because older devices are not required to have SHSH verification with Apple’s server for every firmware restore.
    • Better illustrated in Step 3 of this guide.
  2. Put your phone in DFU mode. Again check this guide if you are not sure how.
  3. Connect your iPhone or iPod to the computer, and launch iREB. Click on the device you have, and it will upload a jailbreak exploit to the phone and prep your phone for the restore. Wait for iREB to tell you it has done the job.
  4. Go to iTunes, it should recognize your iPhone/iPod in recovery mode.
    • On a PC, hold Shift and click on restore. Select the IPSW file you downloaded.
    • On Mac, hold Alt and click on restore.
    • iTunes will now extract the IPSW file and prepare your device for restore.

You device should successfully restore without any error. When I upgraded to 4.2.1, my baseband was also upgraded to 03.10.01. I just want to confirm for others that iOS 4.1 can indeed work with the newer baseband.

Good luck, and hope Apple fixes all the issues with another update soon!

  • Steve McGrath

    Huge, HUGE thank you for the iReb recommendation! Error 1600 had me going crazy, then II found this guide & flew through the downgrade 1st time!!

  • Frank Leng

    Hey Steve. glad this could help.
    I was stuck on 1600 for a while too.

  • acrylic glasses

    great post.thank you for sharing

  • Frank Leng

    glad it could help. take care. :)

  • OLU

    Hi!! I’m a newbie… My iphone 4 is bricked after unknowingly updating to 4.2.1. Not an AT&T customer so my sim does not work and phone is no longer activated. Any help please.. No knowledge of SHSH blobs etc..

  • jdcatcher5252

    I have been trying to downgrade to 4.1 and it goes through the entire restore process and then I get error 1004. any ideas how to get past this?