Downgrading Your iPhone From iOS5 to iOS4.3.3: It Ain’t Easy

Like lots of other iPhone owners, I was excited about the announcement on Monday of iOS5, and all the new features. I don’t like to wait and since it isn’t going to be released until September, I had to get it somehow. Since I’m an iOS developer, I was able to download a developer seed of iOS5 and install it on my iPhone 3GS. I did so Tuesday morning.

It was painfully slow on the 3GS. Granted this is just beta 1, and it will probably improve before it launches, but it was nearly unusable.

So today, I went out and bought an iPhone 4. I had been wanting one for a long time anyway, and my contract was up in February so I’ve been able to get a subsidized price since then… Anyway, I bought a 4, and was not planning on putting iOS5 on it just yet. But when I attached it to iTunes and tried to restore my last 3GS backup to it, iTunes wouldn’t let me because the backup was of iOS5 and the iPhone 4 was running 4.3.3. So, against my better judgment, I installed iOS5 on it.

Big mistake.

While speed was no longer an issue, bugginess was. Lots of 3rd-party apps just seemed to not work right, and even some features of iOS were a bit squirrelly. A downgrade was in order. But, as the release notes tell you, you can’t downgrade.

Well, you can, but it’s a major pain in the butt. Below is a list of what I did to restore mine. But first, please be aware that your mileage may vary, use at your own risk, by reading this, you agree that I am not liable for any damage to your iPhone, iTunes, data, computer, house, car, cat, dog or anything else.

(This is in list form, but it’s not an instruction list, per se. It’s a list of what I did, thus the verbs are in the past tense.)

  1. Restored the entire ~/Library/Application Support/MobileSync/Backup directory from Monday, before I did the upgrade of the 3GS, using Time Machine. (On Windows, the directory is C:Users<UserName>AppDataRoamingApple ComputerMobileSyncBackup)
  2. Downloaded the iOS 4.3.3 software image from links here (the links go to Apple)
  3. Launched iTunes, but hit the little ‘X’ button in the top area to stop it from syncing.
  4. Selected the iPhone 4 in the Devices section, then pressed Option while clicking on the “Check for Update” button. This popped up a dialog to find the .ipsw file that I had downloaded. I navigated to where I had saved it, and selected it.
  5. iTunes started to restore it, then barfed with one of those “unknown” errors. It did leave the iPhone in recovery mode.
  6. Out of paranoia, I shut down iTunes, deleted the partial backup that it had tried to do, thus leaving the Backup directory as it was on Monday.
  7. Started iTunes.
  8. iTunes popped up a dialog saying that the phone was in recovery mode and did I want to restore it. I said “yes.”
  9. It then showed me the EULA for 4.3.3, re-downloaded the .ipsw, then started the restore.
  10. Ten minutes later, it rebooted and showed up in iTunes, with iTunes asking if I wanted to restore it from one of my backups.
  11. I selected the 3GS backup and off it went.
  12. When the phone rebooted, iTunes started re-syncing it.
  13. Half an hour more, and it was done restoring all my data and settings. Then it started restoring 4,500 songs, which takes about 3 hours.

So, that’s it. All in all, it took me about 2 hours, start to finish. If you don’t have a backup of the Backup directory, you’re screwed.

I use pre-release software all the time, but this is the first time I’ve really, truly, gotten burned by it. I have now learned my lesson, and will at least wait for the release of iOS5… beta… 3 before trying again. 🙂