How to upgrade from an older Mac operating system to macOS Catalina or Big Sur

Many people remember Mac OS X 10.6.8 fondly. Not just 10.6 Snow Leopard, but particularly its very mature 10.6.8 release, the final one in that series. It’s considered a stable and perfectly fine version. It’s not a problem—until they want to move to a newer system, particularly macOS Catalina or Big Sur, and find there’s no migration path.

Apple offers Migration Assistant both when setting up a Mac (whether new or erased) and as an app within macOS, particularly to migrate user accounts and applications. As a source, you can use a Time Machine backup, a disk image copy of your macOS startup volume (via a cloning app, for instance), or another Mac.

But Migration Assistant has its limits: in Catalina and Big Sur, you must migrate from Mac OS X 10.11 El Capitan or later. Attempts to copy from older installations lead to an error.

However, you’re not stuck. You have several alternatives you can try.

Upgrade past 10.6.8

It may seem like a pain, but if you have a computer that can be upgraded to 10.11 El Capitan or later, that’s your best bet. This list of models from One World Computing will help you figure out if your Mac can be upgraded that far. It covers years of Mac releases.

Apple has instructions on installing a terminal release of Mac OS X or macOS for its old computers.

Once upgraded to El Capitan or later, you can then run Migration Assistant to transfer data to Catalina or Big Sur.

If your computer’s last OS option isn’t El Capitan, read on.