I currently have Mac OS X Mavericks. When I try to download Yosemite from the App Store the file begins to download and shows an estimated time. After a few minutes the file stops downloading and the estimated time is now replaced by "calculating". After calculating for a minute or so the App Store stops trying to download and shows an error has occurred.
I have deleted the file and started fresh several times and restarted my computer each time ending up with the same error each time.
All of my updates have been installed.