Install operating system on Imac
I used migration assistant to create an external copy of my operating system HD onto a portable USB Drive. Tested the launch of that drive by using the "Command R" to identify the new startup disc. Everything so far went as planned, system launched without a hitch. Then I replaced the failing HD in the IMac 2010 mid year version and expected to be able to just do the same thing. Launch from the external operating system and use the migration assistant to copy the operating system and files back to the new HD in the IMac. No such luck! The migration assistant does not recognize the external drive.
Is there a work around?
iMac 27", macOS 10.13