Yosemite migration assistant locks on start, no way to boot anything else I have a 2011 MBP Yosemite development 2011 machine that will not upgrade cleanly to Sierra, too many weird tools installed there I suppose. So I got another MBP from the same era, wiped the drive, installed Sierra, and planned to use Migration Assistant to move what I could. I plugged in an Ethernet cable, set the new machine as destination, and started the Yosemite Migration Assistant on the old machine, thinking to use it as the source. However, it hung on start and I cannot restart the machine to anything but the same Migration Assistant screen.

I tried rebooting with option key down to pick the drive, but it showed me two of my boot drive, neither one works, then I did recovery boot and fixed the boot drive. Then I did the reset PRAM boot three times in a row. Nothing gets me past the locked up Migration Assistant. When I boot I see a flash of the normal start, then it goes to a screen that says:

Transferring you information
Finishing you Migration

This Mac
Starting up...


Any idea on how I can get my disk to skip this switch to Migration Assistant on boot? The reason I was doing this today was that last night my Time Machine drive failed and I could not recover it and I thought to migrate to a different machine immediately instead of waiting for a new drive to arrive so that I'd be on two drives and upgraded to Sierra. So, I lost my Time Machine backups and cannot recover that. I suppose I can just pull the drive and put it in an enclosure and recover what I can, but I'd really like to be able to boot normally and make a full backup.
I used Disk Utility from recovery to clone the boot drive as an emergency backup since I no longer had a working time machine backup. When it finished it rebooted half way, glitched the screen and then went back to a normal boot up and I could access the machine as usual. All ok so far.

I suspect that it had something to do with connecting an Ethernet cable to a Yosemite machine while trying to do a migration. I'll not do that again.