Transfer from a Mac mini (late 2009) to a Mac mini 2020

Migrating over your local network is slow and highly prone to fail.

Migrating over a direct Ethernet to Ethernet connect is better, but still slow.

The fastest and easiest way to Migrate from your old Mac's Time Machine backup drive.

see > Transfer to a new Mac with Migration Assistant - Apple Support

If you do not have a Time Machine backup get a USB external drive and make one of the old Mac mini to migrate from.

see > Back up your Mac with Time Machine - Apple Support

Another option is to manually copy your music, photos, doc's and other files to an external drive and then manually copy those over to the new Mac mini.

den.thed has the definitive answer. Many years ago I worked for an Apple reseller who tasked me with finding the best way for customers to migrate from one computer to another. I tested all the various options and periodically revisited them as Apple changed hardware specifications. The top method for the vast majority of users still remains using a TimeMachine backup on an external drive.

Personally, and without contradicting “the” preferred manner, i am a fan of taking the opportunity for a real cleanup.

that means longer, but yes: everything (data only) on an external drive.

then reinstall apps from scratch (latest compatible versions). It may allow you to realize yoo no longer need to occupy real estate on your internal drive for an app you have not used for years and no plans either to use it!

then, same reality when moving back your data: your 76 copies of same picture may not be necessary. Other data may live happily on an external drive or in a dropbox or elsewhere. Data from your wife’s profile (and that profile itself) may no longer be necessary now that she has it on her own mac (or if you replaced her 🤣)….

More importantly, you are limiting risks to bring back corrupted data or programs to the new mac 🤷🏽‍♂️

Yeah, that means a few hours +++ but it may be a better investment than later having to cope with lack of space, an unidentified issue with a culprit you brought back….

lanstrad1 wrote:

Personally, and without contradicting “the” preferred manner, i am a fan of taking the opportunity for a real cleanup.

[...]

Yeah, that means a few hours +++ but it may be a better investment than later having to cope with lack of space, an unidentified issue with a culprit you brought back….

I am in the same camp and do that in every major macOS upgrade by erasing the internal device. It needs some planning and a tidy filing system where you know where every important and maybe by default hidden data is and how to manually restore it.

Rest of the family just upgrade new macOS on top of the old year after year with no problems. Or use Time Machine to restore from Carbon Copy Cloner backups when setting up a new Mac. Periodically I force them to do a CCC backup to the external disks I have bought them...