Just remove invalid ports and links in Handbook. The links or ports that can be replaced I have already done so.
sysutils/cdrtools-devel move to misc/schilytools
print/apsfilter port deleted on 2018-09-30
print/enscript move to chinese/enscript
http://www.transcoding.org/cgi-bin/transcode 404 and the original site cannot be found
multimedia/pvr250 port deleted on 2014-09-07
multimedia/pvrxxx port deleted on 2014-09-07
http://www.washington.edu/alpine/ move to https://mailman12.u.washington.edu/mailman/listinfo/alpine-info
net/openldap-server move to net/openldap26-server
https://lists.freebsd.org/subscription/freebsd-realtime: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-vuxml: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-isdn: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-eclipse: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-tokenring: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-new-bus: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-teaching: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-proliant: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-cluster: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-sparc64: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-platforms: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-wip-status: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-firewire: Failed: Network error (status code: 404)
https://docs.freebsd.org/en/books/handbook/eresources/%7Bfreebsd-risc-url%7D: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-atm: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-user-groups: Failed: Network error (status code: 404)
https://lists.freebsd.org/subscription/freebsd-bugbusters: Failed: Network error (status code: 404)
www/apache24 not apache24
https://www.freebsd.org/doc/gr/articles/greek-language-support/: Failed: Network error (status code: 404)
http://netlab.cse.yzu.edu.tw/: Timeout (status code: TIMEOUT)
http://netlab.cse.yzu.edu.tw/~statue/freebsd/zh-tut/: Timeout (status code: TIMEOUT)
mail/dovecot2 move to mail/dovecot
https://ark.intel.com/content/www/us/en/ark/search/featurefilter.html?productType=873&0_ExtendedPageTables=True can't found any things about EPT.
https://uefi.org/specs/ACPI/6.4/Apx_B_Video_Extensions/Apx_B_Video_Extensions.html move to https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/Apx_B_Video_Extensions/Apx_B_Video_Extensions.html
http://acpi.info/spec.htm: Failed: Network error (status code: ERR) and should be The ACPI 6.4 Specification (https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf)
www/apache22 update to www/apache24
http://world.std.com/~reinhold/diceware.htm move to https://std.com/~reinhold/diceware.html
Renamed xen-tools and emulators/xen-kernel/
net/freenet6 port deleted on 2021-04-12
audio/workman port deleted on 2020-06-05
http://www.undocprint.org/formats/page: Failed: Network error (status code: 404)
xorg-server should be x11-servers/xorg-server
vietnamese/xvnkb port deleted on 2014-09-01
japanese/scim-prime port deleted on 2014-09-06
chinese/cce port deleted on 2015-11-28
chinese/zhcon port deleted on 2014-09-01
korean/imhangul move to korean/imhangul-gtk3
japanese/im-ja port deleted on 2022-07-27
chinese/big5con port deleted on 2014-07-24
chinese/oxim port deleted on 2015-11-28
chinese/kon2 port deleted on 2015-11-28
dns/bind99 update to dns/bind918
www/py-djang port deleted on 2022-06-30
www/rubygem-rails port deleted on 2017-01-07
cyrus-sasl2 should be security/cyrus-sasl2
www/mod_auth_kerb move to www/mod_auth_kerb2
http://mgetty.greenie.net/doc/mgetty_toc.html move to http://mgetty.greenie.net/doc/mgetty.html
net/zebra port deleted on 2021-12-31 and should be used net/frr7
https://www.freebsd.org/ports/editors/: Failed: Network error (status code: 404) and move to https://cgit.freebsd.org/ports/tree/editors
https://www.freebsd.org/ports/graphics/: Failed: Network error (status code: 404) and move to https://cgit.freebsd.org/ports/tree/graphics
http://www.ed.ac.uk/information-services/help-consultancy/is-skills/catalogue/program-op-sys-catalogue/unix1: Failed: Network error (status code: 404)
http://www.cs.duke.edu/csl/docs/unix_course/: Failed: Network error (status code: 404) and move to https://physics.osu.edu/courses/cse-4251
http://renaud.waldura.com/doc/freebsd/pppoe/: Failed: Network error (status code: ERR)
rr-pppoe should be net/rp-pppoe
http://ftp5.tw.freebsd.org/pub/FreeBSD: Timeout (status code: TIMEOUT)
http://ftp.si.freebsd.org/pub/FreeBSD: Timeout (status code: TIMEOUT)
http://ftp2.br.freebsd.org/FreeBSD: Failed: Network error (status code: 503)