Migration to new Mac, interrupted by power outage

My wife just got a new M1 MacMini, which came preloaded with Big Sur. During the initial setup, we had begun transferring the files from her old iMac using Migration Assistance (from the Mini). While the files were coming over we had several power fluctuations, and then the power went off for 10-15 minutes. Obviously both computers went dark.

When the power was restored I was not sure what to do, since this had never happened in my 24 years as a Mac user. There is not much information online about this unique problem, but I researched the Apple Forums, and found one person’s advice to restore the MacMini computer from scratch, which means loading the system again. That is a big project, and I thought maybe unnecessary.

I booted both computers, and from the Mini I began the Migration Assistant again. A screen soon appeared which essentially said, “The user ‘BettySue’ already exists on this MacMini. Do you want to delete this user, and replace it with the ‘BettySue’ from the iMac - or do you want to keep ‘BettySue’ and install a second user named ‘BettySue2’ ?” I had never seen this screen before.

I selected option A, which entirely deleted the original unfinished attempt at bringing Betty’s files to the new computer. Then it simply migrated Betty as the one and only new user as if nothing had happened. The MacMini is all setup.

I leave this little tidbit of advice for the next person who might have an interruption during file transfer to a new computer. I don’t know how far back this solution is built into the Migration software, but at least starts at Big Sur. Good luck.