Not Quite a Blog

Warning: The following assumes that you have a 2G iPhone, a Mac laptop or desktop and some familiarity with the command-line.

I just had perhaps the most painless iPhone OS upgrade from 3.0.1 to 3.1. (here is the last installment on upgrading to 3.0.1)

You'll want a copy of the firmware file (IPSW) for iPhone OS 3.1 and PwnageTool from the iPhone Dev Team (you can get iPhone firmware here and PwnageTool 3.1 here). This time we'll create a custom IPSW so get any custom boot logos handy

Here's what you do:

1. Install aptbackup from Cydia if you haven't already. Use it to back up your Cydia apps.
2. Sync with iTunes and be sure that it creates a backup (this will be your reference if you mess up, mostly).
3. Aptbackup has a nasty habit of not working. It really kind of sucks, but it's good for creating a list of installed Cydia apps. So, per this post, SSH into your phone and copy over to your computer the files aptbackup.cydiasources.tgz, aptbackup_dpkg-packages.txt and aptbackup_openssh.tgz found at /var/mobile/Library/Preferences.
4. Open PwnageTool and create a custom IPSW... I'd just recommend following these directions from hackintosh. They work well.
5. You will want to restore from the backup you made earlier using iTunes to get your settings and stuff back.
6. If you're on T-Mobile like me and subscribe to a data plan, you'll want to make sure that you have wap.voicestream.com set as your APN in Settings -> General -> Network -> Cellular Data Network. Otherwise, you'll see an error that reads: "Could not activate cellular data network: You are not subscribed to a cellular data service".
7. To avoid major lameness, don't use AptBackup to actually do the restore. On your computer, do a less aptbackup_dpkg-packages.txt to list the packages that you had installed via Cydia, and manually install them one-by-one. Yeah, it sucks, but it sucks less that not having your AppStore apps! (I had a particularly lame experience with AptBackup trying to use it to restore my Cydia apps. As outlined in this post, after running AptBackup, all my AppStore apps disappeared. They showed up in SBSettings and were still listed in the Applications pane of iTunes, but it appeared as if AptBackup had uninstalled these apps from my phone!)
8. Now it's just a matter of moving your icons to the right place.
9. I'd suggest changing the passwords for both the root and mobile users... from the default of alpine to something more substantial. (To do this, ssh into the phone as root, do passwd for root and then do su mobile to change yourself to the user mobile and do passwd for that user too.)
10. If you use Cycorder, you'll also need to re-establish the symbolic link between where cycorder stores its videos and AirSharing, if you had it set up like that. (Do that as the mobile user so the permissions line up.)

UPDATE [2009-10-05T11:16:56]: added bit about APN to get data network back.