iCloud Photo Library constantly preparing my library on the web
MacBook Pro with Retina display, OS X Yosemite (10.10)
I've been seeing the exact same message for a few days now also.
Preparing your library.... This may take a few minutes
I have written a script that does this once per week, as that's how many times I have this ridiculous issue.
Hey Apple, see Google and copy its cloud products/performance. For once, I'd forgive you for copying and not being copied.
I've had this problem now for almost 3 days.
I'm on Capitan.
iCloud Photo Library constantly preparing my library on the web