Try signing out of the CC desktop app, then sign back in again.
Same problem here. Tried signing out and back in--no go.
Signed back in still wouldn't open.
Tried again and after signing back in to the CC desktop was able to open LR Cloud 2015. Thanks for your help.
Click on your CC icon.
Click on the gear icon.
Click on Preferences.
Sign out of CC.
Sign back in.
Don't click on "Quit."
I had been QUITTING CC and relaunching. Try signing out.
I did same and it worked.
Sent from my iPad
hhasn't worked for me. Been at this a while, now. Time for the beers.
Not working for me either. iMac 27" Retina Yosemite 10.10.3