This ICMP DestinationHostUnreachable code 6 was defined in RFC:1122, then deprecated in RFC:1812:

This code SHOULD NOT be generated since it would imply on the part of the router that the destination network does not exist (net unreachable code 0 SHOULD be used in place of code 6);

lib/main.php:944: Notice: PageInfo: Cannot find action page

lib/main.php:839: Notice: PageInfo: Unknown action