Any recent or kernel modifications you performed
PF can sometimes fail to load or report cryptic errors if permissions are incorrect. /etc/pf.conf is owned by and has permissions set to for better security). Does this error appear immediately after an OS upgrade , or while trying to load a new custom rule ignore_osversion - The FreeBSD Forums pf configuration incompatible with pf program version
A small ISP running FreeBSD 12.2 attempted to upgrade their kernel to FreeBSD 12.3 via freebsd-update but forgot to run freebsd-update install for userland. Upon reboot, the system failed to load the firewall. The error appeared in /var/log/messages : Any recent or kernel modifications you performed PF
However, to pinpoint the specific syntax error rather than a generic "incompatible" message, one must increase verbosity: Upon reboot, the system failed to load the firewall
To ensure compatibility and secure configuration of PF:
sysctl net.pf.version
When you see this error, it means one of three things has occurred: