Indeed, the ease of device transfers and upgrades are one of Apple's best selling points - and truth be told, it usually runs without a hitch. But unfortunately for me... not this time.
As my iPhone rebooted, everything seemed normal... until I went into the Photo Gallery:
All my photos showed up as black squares with no thumbnails!
After the initial panic, I tried to make some sense of it. The photos were still there, and you could even select them and delete them... but the thumbnails showed up as black.
New photos, on the other hand, showed up fine.
First things first! I immediately copied all the photos and video to a backup drive.
Then, after rebooting the iPhone and trying several iTune syncs - without success - I had to resort to the all-knowing friend we have today: "Dear Google, show me what you know about iPhone black photo galleries with black thumbnails."
As expected, there were indeed lots of similar problems reported by other users, some of those coming back from the pre iOS days, with iPhone OS 3.x missing thumbnail reports, but others mentioning precisely the iOS4.
It was odd... so much reports and Apple did nothing to fix this? I was both angry and curious...
Apparently, photo management during upgrades and device transfers doesn't always work as expected.
The first problems were when Apple decided to change the folder structure of photos and its metada. (Truth be told, when I transfered my 3GS data to my iPhone 4, my video thumbnails went missing and were replaced by a "?" sign.)
As I skimmed through forums and google results, I found that most people simply gave up and opted for the easy way out: copy all the photos to new photo albums and sync it through iTunes.
But I'm not a big fan of iTunes, and losing my 1900 photo roll album wasn't something I would give up easily.
How to fix the black thumbnails photo gallery in iPhone?
After a while I was truly convinced this had to do with the cached thumbnails the iPhone stores somewhere.
Indeed I recalled briefly seeing a "rebuilding photo gallery" screen when I rebooted my iOS4.1 iPhone for the first time... but it was quickly gone.
My theory was: that process was interrupted somehow, and the thumbnails were completely corrupted or non-existent.
So, the question now was: How do I force the iPhone to rebuild the Photo Gallery thumbnails?
Some googling later I came across a forum post mentioning some obscure iPhone filesystem files that might have something to do with it.
On the other hand, most of that talk was related to jailbroken iPhones... How was I to access the iPhone file system to get to those files???
Thankfully, i-FunBox does just that: giving you access to the raw iPhone file system, even without jailbreak.
Inside the \PhotoData folder you'll find 3 files:
Without anything else to lose (I had my photos safely backed up), I promptly deleted all 3 files via i-FunBox...
At first, nothing happened, the Photo Gallery was filled with the same black thumbnails, even after terminating and restarting the process.
But, nothing like a real reboot to make sure...
And presto... The Photo Album rebuilding screen showed up once again, and this time it slowly showed its progress across the screen, as it should.
When completed, my iPhone Photo Gallery and Album was perfect, with all the thumbnails showing up - even the video one that were lost in the migration to the iPhone 4.
As a last note; I find it odd that, with the number of people experiencing this problem (and no one is safe from it, as some people say this happened "without notice" - all it takes is a corrupt thumbnail database) why couldn't they tuck away a photo cache reset button somewhere in the setting menu, just like they have a clear cache option for Safari?