The Mac OS X 10.10.3 includes the new iPhoto replacement called Photos. My upgrade experience was not very positive: I could no longer connect to the various albums I shared on iCloud. The albums were still there, they were showing up on other devices, but in Photos they were not visible. The Shared section of Photos showed the message “Connecting to library… Retrieving latest photo sharing activity” but after that, nothing happened.
After trying various things, this is the procedure that fixed it for me:
- Close Photos
- Repair disk permissions via Disk Utility
- Don’t start Photos, but go to System Preferences, iCloud, Photos and disable iCloud Photo Sharing
- Enable it again
- Start Photos. After a while, the activity stream will update and the shared photos will start coming in.