Success Update! Thank you...

[muchacha_grande]

First of all, thanks to all the OPNSense Team.

This time I had to reinstall to move to ZFS, so I exported the configuration with RRD data included and made a full install on a ZFS pool.
The config import was done during installation with the configuration importer from a USB drive.
After the first boot, I reinstalled the plugins and then everything worked fine.
All of this was done on a a VMWare ESXi virtual machine. Now I'm able to use ZFS snapshots instead of ESXi ones.

A really really great work of OPNSense developers.
Thank you and cheers...

[Patrick M. Hausen]

Be aware that with ZFS in the guest OS thin provisioning does not make sense because the copy on write mechanism of ZFS will write every block of your virtual disk, eventually, blowing up the VMDK to maximum size even if there is plenty of space inside the guest.

For best performance use a thick provisioned disk.

[muchacha_grande]

Thank you Patrick. I have it already on a 32 GB thick provisioned vmdk.

Cheers

[hansen97124]

Success here too.  no issues going to OPNSense 25.1 on my CWWK J6412 based HW.