When attempting to update to Catalina, my message reads "OSX not formatted as APFS. Now what?

Hello FabFlamingo,

Thanks for reaching out to the Apple Support Communities. I understand that you're not able to upgrade to macOS Catalina because your hard drive is not formatted for APFS.

This process usually occurs automatically during upgrade. Since you're running macOS Mojave, I recommend that you reinstall Mojave before attempting to upgrade to Catalina: How to reinstall macOS from macOS Recovery

If the issue persists, you should backup your data: How to back up your Mac

Erase the Hard Drive and reformat it to APFS before reinstalling Catalina: How to erase a disk for Mac