Users are experiencing a series of issues--some minor, some significant--after the iPhone OS 2.2.1 update.
Installation fails, cannot restore Several users have reported an issue in which the installation of iPhone OS 2.2.1 fails partway through and subsequent restore attempts fail, yielding, in essence, an unusable iPhone.
If you experienced a similar issue, try the suggestions listed in this article.
Airplane mode problems Make sure that your iPhone is not in airplane mode. If the iPhone is in airplane mode when it is updated, it will not be able to properly activate after the software installation takes place. To get around this, avoid putting your iPhone in airplane mode prior to the update, or (if you've already applied the update in airplane mode), disconnect your iPhone from your computer, then slide the emergency call switch and follow the prompt to disable airplane mode. Press the home button, connect your iPhone back to your computer and allow activation to take place.
Slowness Some users have reported laggy or otherwise poor performance from interface elements under iPhone OS 2.2.1. If you are experiencing a similar issue, please let us know.