How to fix Error 0x80300024 when installing Windows

So, trying a fresh install of Windows onto the second of two drives installed on this new computer. (The second drive was an SSD)

Every time I’d try to install, Windows returned error 0x80300024.

Fortunately, this fix was simple. There was an MSR partition on the first drive. Deleted the MSR partition and that let Windows install onto the second drive!

Summary: A partition on the first drive was preventing Windows installing to a second drive.