I had a mac Pro 2008 with El Capitan that I backed up to a external HD with Time Machine. I traded my Mac Pro for a Mac Mini 2014 which had High Sierra installed. I hooked up my external drive and used migration assistant to transfer my files and apps. The whole thing took a really long time, like overnight, so the next day when I go to see the progress, I see it froze on the restart. So I turned off the mac mini and turned it back on. The restore had created all the users I had on there previously but no files or apps. When I tried to use the migration assistant again, the time machine backup was not recognized. It looks like it got corrupted somehow. I unplugged the external drive, and re-formated and installed El Capitan thinking that might be the issue. Still no luck. Any ideas on how to fix a corrupted drive with time machine on it?