If you have the unfortunate luck to upgrade to version 1.1.2 under iTunes 7.5, and you have a previously jailbroken iphone, you might find that Installer.app breaks.

It breaks because /var/root/Library/Installer/Localpackages.plist still has information about all of your previously installed applications and the iTunes upgrade deletes all of the 3rd party apps that you have installed. Independence and other jailbreak tools also revert the phone to Installer.app version 2.6.3, but Localpackages.plist will still say that you are at version 3.0b7!

What makes this even more difficult is that you will not be able to upgrade or uninstall applications which have been deleted from the phone but not deleted from the plist.

The fix: Once you get SSH up and running on the phone, either rm -rf /var/root/Library/Preferences/Installer , or, manually edit Localpackages.plist and delete all of the apps that are no longer accessible on the phone. Removing the directory entirely works, but it’s not the best solution.

It’s best if you edit the file, changing the currently installed version of Installer.app to “3.0″. Once you’ve done this, run installer again and you will be able to upgrade to the latest version using the Upgrade tab.

Don’t edit the file or sftp a new file in place if you have installer.app running. Powercycle the phone and edit the file before running installer.app! Otherwise, when installer.app quits, it will overwrite Localpackages.plist, clobbering your changes.

You should reboot the phone after editing Localpackages.plist.

Good luck – it took me a few hours to figure this out, and hopefully this will save you time.