Migration Assistant Failing I'm trying to transfer my information from a mid-2012 Macbook Pro Retina running the latest version of Yosemite (10.10.3). The new machine is a 2015 Retina also running Yosemite. 

The first time round I tried doing this via a Thunderbolt cable. The donor machine was booted into target mode, and on the recipient machine I started up the Migration Assistant and followed all the instructions. When the time remaining bar got down to about a minute, it started to creep back up. 

It kept going and going. I left it for an hour and a half (bearing in mind the transfer up until then had taken 20 minutes). It had reached about 17 hours by the time I decided to give up. 

I then formatted the drive and reinstalled Yosemite via the Internet. So starting with a clean state I tried again with method 2 which was via a Timemachine backup. This had exactly the same effect. I'm going to leave it overnight in vein hope that something might happen, however I thought that I might as well ask on here to see if there are any suggestions.

This is similar to another question, New Mac Pro: Setup/Migration Assistant never finishes, and one piece of advice from that is that I should just boot into target mode and manually copy files over. I may well end up doing that, although obviously I don't want to miss anything.
I'd have taken both machines up to 10.10.4 first using the combo updater - as it specifically includes fixes for Migration Assistant.  

Then I'd have followed the instructions rather than try it in target disk mode - you need to be running Migration Assistant on both machines, as you must authorise on both. 

I've successfully migrated two machines in the past month, one from 10.10.4 to 10.10.4  ...the other from Windows XP… &amp; if it can do that, it can do anything ;-)