I have updated to Mountain Lion and want to iCloud synch my photos, I am on version 8.1.2 but when I do so it says Request to the server macappstore://ax.search.itunes.apple.com fail Request to the server macappstore://ax.search.itunes.apple.com failed.

You need to buy the update. Photostream requires iPhoto11.

Contact App Store support. It's an App Store issue, really.

Have exactly the same problem as Anthony Barnett. I upgraded some time ago from Leopard and now have the latest version of Lion on my iMac but of course this does not give you access to iCloud for your photos unless you upgrade iPhoto and the only way to do this is to try and buy iLife '11 from the App Store. I click to buy iLife '11 (though it actually says upgrade to iLife '11) and get a pop up asking to choose an application. This pop up pre-selects iPhoto but when you click on "accept" a message comes up asking whether you want to "join this stream". If you click yes you then get this message "Request to the server macappstores://itunes.apple.com failed." Have tried endless times and each time get the same result. Does anyone have a solution? Contacting the App Store I´m afraid, would be a last resort for any of us who have tried to do so in the past so would be very grateful for guidance - I must be doing something wrong. Maybe Anthony found a solution?