I am trying to transfer things from a Macbook Air to a Macbook Pro Retina. I start up Migration assistant on both and proceed with the initial steps, selecting the source laptop from the target Macbook Pro, then after around 10 seconds on the Macbook Pro I get a screen saying "Migration unexpectedly quit. Please try again." The Macbook air seems oblivious of any issue and continues in a never ending loading stage. Both have all the updates installed. What can be the issue? The migration is being done over Wi-Fi and the username and password for the user account is the same on both laptops. iCloud is not enabled on either. Not sure if any of those things are relevant.