by David Kanter
July 7, 2011
Last week I covered how to upgrade from iOS 4 to iOS 5. My favorite feature in iOS 5 was the new notification system. It was nice to be able to turn on my phone and see my accumulated text messages and twitter @ replies all in one place. That being said, I think I should have installed iOS 5 on my spare 3GS instead of my primary phone because apps I use on a daily basis like Evernote and Dropbox stopped working, and the camera took forever to load. I will probably reinstall Boxcar to consolidate my notifications in one place. Despite warnings from Apple that once you upgrade to iOS 5 you can't go back, I was able to successfully downgrade both my iPad 2 and iPhone 4 from iOS 5 beta 2 back to iOS 4.3.3. I can only say this worked for me on two iOS devices, but will repeat that Apple does not recommend you do this. For the purposes of is article I will cover how to downgrade on the iPhone 4 running iOS 5 beta 2 to iOS 4.3.3 using iTunes 10.5 on a Mac. If you backed up your iPhone 4 on 4.3.3 before you upgraded to iOS 5 beta 2 you will also be able to restore to the point in time just before you upgraded. Unfortunately, any data you had in iOS 5 or saved in iCloud will be lost. The first thing you'll want to do is to put your phone into DFU mode (device firmware upgrade mode). This will basically tell the phone it is ready for a new OS upgrade (in our case it will be an older OS). Putting your phone into DFU mode can be tricky, and I had to do this about five times before I got it right: 1. While powered on, plug your iPhone into your Mac and let it sync. Wait for the operation to finish. When the sync is done, power down the phone and leave the USB cable connected. 2. Hold down the iPhone's power and home buttons at the same time for 10 seconds. After 10 seconds is up release only the power button and continue holding down the home button. 3. After a few more seconds, iTunes should tell you that recovery mode has been detected and will ask you if you want to restore the phone. The iPhone screen will be black. this .ipsw file for my iPhone 4 running on AT&T (direct download from Apple). You will need a different .ipsw file if you have a 3GS or a Verizon iPhone. Searching Google should help you quickly find the correct 4.3.3 .ipsw file, but be sure it's from a reliable source such as Apple.