On the newer install media (OPNsense-26.1.2-dvd-amd64.iso) and (OPNsense-26.1.2-vga-amd64.img) when installing onto a machine with a unformated hard drive, you can't use the Install (UFS) option without being presented with this error:
(https://i.imgur.com/wXPvaqM.png)
The only workaround is to Install via other modes >> then use Auto (UFS)
for some reason it will create the proper partitions, if you need a bigger swap partition like 8GB as presented with the main installer you can do it then.
If you have a partition table or any partitions already written to target disk, then this bug isn't present. For some reason the newer install media 26.1.2 tries to destroy a geom before formatting a blank disk. The 26.1 install media before this worked just fine.
I've tested my hardware and verified my hashes, and i'd suggest you try this on a blank VM.
Yes true because during testing we've constantly run into random errors with the UFS installer not working without a proper destroy.
https://github.com/opnsense/installer/commit/805d33dff20b
I can relax that to not make it a hard error (destroying a destroyed disk is debatable as an error code but it is what it is), but there will be no new images. The 26.1 one is still available as well.
Cheers,
Franco