My home devices is mostly Apple The integration is superb, but I fear the vendor lock-in.

Last week I tried to sync some pictures from Aperture to my iPad. Following the instructions from Apple it should be really simple. Just select the app/library you want to sync, check the albums and press sync. Unfortunately I was stuck on the first step.

I used to have iPhoto for managing my pictures but recently switched to Aperture. (I know it is going away) Thanks to Apple forward thinking Aperture could just use the iPhoto library. No need to migrate or import all my pictures. This turned out to be the issue.

To free up space (1.6Gb) on my SSD I removed the iPhoto app. Aperture worked like a charm and I didn’t even notice the sync in iTunes missing.

After some playing around with caches, small test libraries, recreated previews and library rebuilds I decided to bring back iPhoto. Since I don’t update to Yosemite (10.10) the App store wasn’t the place for me to get iPhoto. Luckily I use TimeMachine and could restore from there.

With iPhoto back in the Applications folder the option to sync with the library was back in iTunes. Check the albums and sync … just works.

TLDR

Make sure you have installed the app that created the library in order to sync to your iDevices with iTunes.

References

Sync photos on apple support
Aperture Library Not Showing Up on photoapps.expert