SOLVED: linker_load_file: /boot/modules/openzfs.ko – unsupported file type

While trying to recover and upgrade a FreeBSD install we ran into an issue where the kernel loader would hang when loading openzfs.ko:

linker_load_file: /boot/modules/openzfs.ko - unsupported file type

In this case /boot/loader.conf had auto-importing enabled via this:

vfs.zfs.autoimport_disable=0

The default is 1, or disable auto import, since at least 2014 according to this commit. In this case there was a disk from another zpool put into the server and it was trying to auto-mount that but couldn’t due to it being broken.

Removing the line let us boot the server and clean it up.