pfSense

1) Have an old config with a rule that specifies Protocol ICMP and ICMP type "Echo Request" (for example)
The old rule should be from a previous version where:
<ipprotocol>inet</ipprotocol>
was not stored in the rule config XML.
The rule must not have a gateway specified, and must not be on a WAN-interface that has an IPv4 address (if either of these conditions are true, then the rule is written with an IPv4 gateway specified, or a reply-to clause with an IPv4 address - which seems to allow pf to deduce that it is an "inet" rule)
2) Use the rule in a system upgraded to 2.3.3

Errors are reported like:
There were error(s) loading the rules: /tmp/rules.debug:247: must indicate address family with icmp-type/code - The line in question reads [247]: pass in quick on $WANIF proto icmp from $ahRemoteManagement to $ahWanVip icmp-type echoreq tracker 1463665353 keep state label "USER_RULE: ICMP monitoring"
@ 2017-02-22 16:22:43

See forum https://forum.pfsense.org/index.php?topic=126031.0