The previous port of Knot DNS, dns/knot1, is starting to complain about build failouts. As I expect all users already migrated to dns/knot2 I'm convinced that deleting the port is the best solution. I tried to make a patch to do so, but it didn't look too useful.
A commit references this bug: Author: riggs Date: Sun Nov 18 08:01:37 UTC 2018 New revision: 485217 URL: https://svnweb.freebsd.org/changeset/ports/485217 Log: Mark DEPRECATED. EOL upstream, and successor already in place PR: 233163 Reported by: freebsd@dns.company (maintainer) Changes: head/dns/knot1/Makefile
Expired port removed.