time machine and migration

[thewall]

I had time machine running on my iMac running Mavericks i have now transfered all data to a new iMac running El Capitian, when i did the migration i unplugged the time machine hard drive as when it was installed the migration would not work, what now do i just plug it in or do i have to reformat the hard drive and start again which isn't a problem if thats the easiest

 

[JohnDS]

The easiest thing to do is to erase the Time Machine hard drive, making sure you format it as Apple Extended Format (Journalled), then start a fresh backup.