Monterey | Disk Prep | Partitons & your experience

I got an ssd for my 2015 mac. I run it outboard on USB 3.0 because I can find no way to get an old thunderbolt to be able to see it even with cables that are to make the transitions. Partitioned it in half.

Mojave runs like a deer compared with the internal hard Disk. The other has a clean install of Monterey and the rest got filled in with Migration assistant. Eliminate programs that don't run under Monterey and all apprears to go well, but when I boot on the old Mojave partition, or the original hard drive:

"This disk has features inconsistant with this OS."

Does Apple have a FAQ on this?

BTW: the external SSD was formatted APFS and then partitioned.

Time Machine was handled the same way.

Disk Utility is not happy.

Techtool 15 is not happy.

Current Strategy: Clean Install on another dirve, more migration assistant, and when candles all light up a clone back to a wiped ssd.

Let me know what works/ what I should not be doing.

-wbajr tbc

This is about a "Late Nov 2015" iMac desktop machine.

Runs monterey like a dream.

Oh, and if i'm in the wrong area of this discussion board feel free to tell me where this should be.