Running Catalina & Mojave on same computer

Howies121 wrote:

I'm running Catalina 10.15.7 but I have a business program that can only run on Mojave or less down to 10.7. Can I partition my drive so I can have access to either OS?

yes, you could do that. but from what I can tell, that option is fraught with potential problems. I too have a need for an older macOS intermittently. but I don't dual boot from my local drive. I keep the local drive up to date (currently Ventura) and I have Catalina on an external Samsung T7 SSD. and an added bonus of running each macOS on separate drives, i'l not likely to lose both macOS at the same time because of a drive failure.

yes, I looked at that. and it is of course possible to partition the local drive and dual boot from it. I didn't say it could not be done. but because I have seen issues here many times while trying it, IMHO it is a bad idea to do that.

Coincidentally just read an almost identical question which I partcipated in - it was solved - last post page 2

Create partition on APFS internal disk to… - Apple Community

and I should have added, you will only be able to run Mojave if the Mac is actually compatible with Mojave.

you're welcome. :)