Ok I'm having the issue of the app store and updates not working at all. I open up the app store and get the spinning wheel of death. I'm on iMac Retina 5k, 27-inch, Mid 2015 running OS X Yosemite version 10.10.3
From looking around it seems my wife had tried to torrent some software but I have deleted all such programs and clients.
IMAC (RETINA 5K, 27-INCH, MID 2015), iOS 8.4
I am experiencing the exact same issue on the exact same machine today. I haven't attempted to torrent anything or do anything out of the ordinary.
After the spinning wheel of death spun for over an hour, I received an error message. "Error Occurred. Couldn't communicate with another application."
Once I let the spinning wheel of death in the App Store run its course, I got an error message. I then closed and restarted App Store and was able to see the Yosemite 10.10.4 update. I did the update. Issues with App Store and other issue I was having with blinking in Finder and any open windows stopped.
It took over an hour of the spinning wheel to get the error message.
App store won't load or update
