After reinstalling iOS 8.4.1 on my iPad Air (due to some issues with the 9.0 developer betas), I was unable to use either FaceTime or Messages. When I'd enter my iCloud credentials in the setup box for either service, I'd be greeted by a long delay, followed by this error message:
An error occurred during activation. Try again.
When I searched on this message, I got lots of hits, including the first one, which points to this article:
The advice in this article matches what I was told by Apple Support: back up the iPad, erase it, set it up as new, make sure Messages/FaceTime works, then restore from backup. And for me, it seemed to work at first: Everything worked fine until I did the restore, and that would then break Messages/FaceTime. Ugh.
Apple Support told me the backup must be corrupted, and I'd just need to start fresh. But with over 200 apps, and who knows how many that don't sync data via iCloud or other service, I did not want to do this.
But then I noticed something. Something completely self-induced. And that something turned out to be both the problem and the solution. So just what was that something? Nothing more than a bit of time travel…
I use my iPad for a lot of things, including gaming. And some games—very annoyingly—have timers that limit what you can do until the timer advances. In some of these games (mostly the poorly-written ones), the timers run locally on your iPad. So you can advance the timers* by manually setting your iPad's clock forward, then relaunching the game.
* Call this cheating if you like; I call it "playing the game when I have time to play the game, not when the dev wants me to play the game."
Usually when I do this, I then set the clock back immediately (the games don't seem to notice this backwards time travel at all). But for some reason (I blame the kids), I must've gotten distracted and left my iPad running in the future for some period of time. I noticed, for instance, that I had app updates that were shown as being installed in late November of this year—a few months from now. Whoops!
I began to think this might be causing the FaceTime/Messages activation issues. But I wasn't sure how to solve it. While brainstorming with my buddy Kirk, I thought that maybe if I jumped back to the future, I might be able to activate FaceTime and Messages, as the iPad would be back in what it thought to be the "right" period of time.
So I set my clock forward to December of this year, and attempted to sign in on FaceTime and Messages. Neither actually seemed to work, but they didn't throw the error message either—they just sat at Verifying.
While they were sitting there thinking about verifying, I switched the time back to automatically set, then went back to look at Messages and FaceTime in Settings. At first, nothing was different…but then, after a minute or so, both popped up as logged in and enabled. Hooray!
So net net, I caused myself much trouble by playing with time. (That's what always happens in the movies, right? I should've known better.) If you've been similarly bit by the activation issue, and the erase/restore method linked above doesn't work for you…perhaps a little time travel will do the trick.