Migration Transfer

Please carefully read the information in Setup Assistant and Migration Assistant. This will provide instructions and no the information on the old (in your case an iMac) will not be erased. NEVER EVER migrate using Wi-Fi and DO NOT connect Mac to Mac using a cable. If you do not have a Time Machine backup of the old computer, please create one! Back up your Mac with Time Machine

The drive most experienced users on these forums like is the OWC Mercury Elite Pro due to it great cooling (translates into longevity) reasonable price, great service, and when the internal HD dies (eventually all HD's die) you can replace it within 5 minutes.

I recommend against using the cheap drives like the WD enclosure, Seagate enclosures as those are throw away (you cannot replace the HD), and due to inadequate cooling they tend to not live as long.

I started migrating my files from my old IMac 21” to my new Mac mini M1 (2020) as instructed from the Apple website. It’s been 24 hours when both Mac said transfer was finished. But when I re-booted my Mac mini, it said resuming migration eventhough my old iMac 21” is already shutdown. The computer icon on the Mac mini is now the Mac mini and not the old IMac 21”. It’s been 2 hours now so I’m thinking if I should cancel and re-start or wait… Help needed.

Please be specific, there are many ways to for Migration Assistant to start, the most reliable method is what I suggested in my post of December 7th, 11:11 AM. If you used ANY other method it will likely fail. This is why I suggested using this method!

How are you transferring your data? (Wi-Fi, Time Machine, etc.)

I followed the instructions from Apple to connect both Macs by a thunderbolt cable before I read your post to back up from Time machine.

I attached a thunderbolt cable to both macs. I believe it said transferring by Ethernet.

Then you need to execute the instructions I suggested.