From the early pfSense menu in console: Boot Single user
I entered these commands:

mount -o rw /
mount_msdosfs /dev/da0s1 /media
cp /cf/conf/config.xml /media

I used the same ISO pfSense image version as the pfSense VM version that crashed to build a new default pfSense VM, then I imported the config.xml.

That worked for me.

Thank you for the pfSenseBackup solution. The author also provides a Linux version I will try for sure.

in a virtual machine

The VM manager doesn't permit you to 'browse' the file system offline ?

@padhi said in It was not possible to identify which pfSense kernel is installed:

but they quickly go outside the console window

Even the dumb 'free' Hyper-V permits to log the console. For easy analysis afterwards. Yours ?

edit :
Example : as I'm using this one : https://github.com/KoenZomers/pfSenseBackup/blob/master/README.md

So all you need is a Windows PC. Set it up so that every day a xx h it grabs a backup.
Or have it backup when you start (boot) it.
Now your taking the advantage of the fact that if you have a very recent backup, you'll never need it

That did not help because pfSense is run from an img file (not directly from a disk).

Under Ubuntu, I tried to mount the ufs filesystem using losetup -P and mount -t ufs -o ufstype=ufs2 but that failed because loop<n>p1 is not created.

Of course I have a backup of config.xml file but it is not the very last.

I understand that the current pfSense img file I have is not working anymore and I get no evidence in logs that an event could explain this situation.

If you see something else, do not hesitate. Thank you.