Data migration unable to connect
When attempting to transfer data from old MacBook to new MacBook using migration get error message unable to connect
When attempting to transfer data from old MacBook to new MacBook using migration get error message unable to connect
Sounds as if you're trying to use Migration Assistant via WiFi?
I recommend using either a Time Machine backup external drive or direct cable connection. (The type of cable would be determined by the specific older Mac you're transferring from). WiFi migration is prone to issues like you've experienced.
See if this link may be helpful in getting your problem sorted out.
Data migration unable to connect