This ICMP DestinationUnreachable code 0x7. This message means that the LinkLayer? can tell that a host authoratively does not exist, as opposed to DestinationHostUnreachable which means that it is simply unreachable.

Linux converts this to a EHOSTDOWN error return.

This is defined in RFC:1812 Section

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

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