Recently I ran into a problem with PFSense. After rebooting I noticed several errors during the boot proces.
I was able to boot into the single user environment and after some investigating I found a solution that worked for me.
pkg-static update -f
pkg-static upgrade -f
After rebooting I noticed that there were some (file) lockes and I had to update the kernel (otherwise PFSense keeps on booting in a loop) using the 13 option in the menu (type exit to go to the menu)
After this I had to reboot the PFSense and after spinning up I was able to open the Web interface and found out that everything was working again.