diff --git a/_data/presentations.yml b/_data/presentations.yml
index 3c7a06242a3ce9915fc1849cedcf60d506a48dd8..07584c87fc2e1b4468a3ec63fe69be3a52c0c356 100644
--- a/_data/presentations.yml
+++ b/_data/presentations.yml
@@ -60,7 +60,6 @@
     date: 2023-07-16
   video:
     url: https://archive.org/details/fossy2023_Breaking_the_Chains_of_Trustin
-  slides: https://cascadia.debian.net/~vagrant/breaking-the-chains/Breaking_the_Chains_of_Trusting_Trust.pdf
 
 - title: Reproducible Builds - the first ten years
   presented_by: Holger Levsen
@@ -207,16 +206,14 @@
     location: Montréal, Canada
   video:
     url: https://www.youtube.com/watch?v=56nRFxA7lPY
-  slides: https://www.aikidev.net/~vagrant/Reproducible-Toolchains-For-The-Win.pdf
+  slides: https://people.debian.org/~vagrant/Reproducible-Toolchains-For-The-Win.pdf
 
 - title: There and back again, reproducibly!
   presented_by: Vagrant Cascadian, Holger Levsen
   event:
-    url: https://cfp.linuxdev-br.net/2019/talk/VH9CCY/
     name: Linux Developer Conference Brazil 2019
     date: 2019-08-04
     location: Sao Paulo, Brasil
-  slides: https://cfp.linuxdev-br.net/media/There-and-Back-Again-Reproducibly-linuxdevbr.pdf
 
 - title: Reproducible Builds - aiming for bullseye
   presented_by: Holger Levsen, Chris Lamb, Vagrant Cascadian
@@ -227,7 +224,6 @@
     location: Curitiba, Brasil
   video:
     url: https://meetings-archive.debian.net/pub/debian-meetings/2019/DebConf19/reproducible-builds-aiming-for-bullseye.webm
-  slides: http://layer-acht.org/slides/2019-07-21-DebConf19-RB-aiming-for-bullseye/
 
 - title: Reproducible Builds aiming for bullseye
   presented_by: Holger Levsen, Jelle van der Waa
@@ -238,7 +234,6 @@
     location: Hamburg, Germany
   video:
     url: https://meetings-archive.debian.net/pub/debian-meetings/2019/miniconf-hamburg/reproducible-builds.webm
-  slides: http://layer-acht.org/slides/2019-06-08-MiniDebConf-Hamburg--aiming-for-bullseye/
 
 - title: Reproducible Builds in der Wirklichkeit
   presented_by: Holger Levsen
@@ -420,7 +415,6 @@
 - title: You think you're not a target? A tale of 3 developers…
   presented_by: Holger Levsen
   event:
-    url: https://minidebconf.curitiba.br/2018/en/
     name: MiniDebConf Brasil
     date: 2018-04-13
     location: Curitiba, Brazil
@@ -481,7 +475,7 @@
 - title: You think you're not a target? A tale of 3 developers…
   presented_by: Chris Lamb
   event:
-    url: https://freenode.live/
+    url: https://old.freenode.net/
     name: Freenode Live
     date: 2017-10-28
     location: Bristol, United Kingdom
@@ -503,7 +497,6 @@
     location: Bornholm, Denmark
   video:
     youtube: CE7091U-u2I
-  slides: http://layer-acht.org/slides/2017-08-27-bornhack/
 
 - title: Reproducible Builds status update
   presented_by: Chris Lamb, Holger Levsen, Maria Glukhova, Steven Chamberlain, Vagrant Cascadian, Valerie Young & Ximin Luo
@@ -527,7 +520,6 @@
   video:
     url: https://meetings-archive.debian.net/pub/debian-meetings/2017/debconf17/fun-with-buildinfo.vp9.webm
     youtube: LN_P3aEBGR0
-  slides: https://annex.debconf.org/debconf-share/debconf17/slides/91-fun_with_buildinfo.md
 
 - title: A 2-minute pitch for Reproducible Builds
   presented_by: Arnout Engelen
@@ -543,7 +535,7 @@
 - title: Reproducible builds
   presented_by: Chris Lamb
   event:
-    url: https://www.lfasiallc.com/linuxcon-containercon-cloudopen-china
+    url: https://lc3china2017.sched.com/
     date: 2017-06-19
     name: LinuxCon + ContainerCon + CloudOpen China
     location: Beijing, People's Republic of China
@@ -559,7 +551,6 @@
 - title: Reproducible builds
   presented_by: Chris Lamb
   event:
-    url: https://oscal.openlabs.cc
     date: 2017-05-13
     name: OSCAL'17
     location: Tirana, Albania
@@ -603,13 +594,6 @@
     name: Libreplanet 2017
     location: MIT, Cambridge, United States
 
-- title: Reproducible Builds everywhere
-  presented_by: Holger Levsen
-  event:
-    url: https://www.guug.de/veranstaltungen/ffg2017/
-    name: GUUG Frühjahrsfachgespräch 2017
-    location: Darmstadt, Germany
-
 - title: Introduction to Reproducible builds
   presented_by: Vagrant Cascadian
   event:
@@ -620,7 +604,7 @@
 - title: Reproducible Builds everywhere
   presented_by: Holger Levsen
   event:
-    url: https://ffg.guug.de/
+    url: https://www.guug.de/veranstaltungen/ffg2017/
     name: GUUG Frühjahrsfachgespräch 2017
     date: 2017-03-24
     location: Darmstadt, Germany
@@ -638,7 +622,6 @@
 - title: Reproducible Builds and Fedora
   presented_by: Dennis Gilmore, Holger Levsen
   event:
-    url: https://www.redhat.com/en/events/devconfcz-2017
     name: DevConf.cz
     date: 2017-01-27
     location: Brno, Czech Republic
@@ -758,8 +741,7 @@
     location: Brussels, Belgium
   video:
     url: http://video.fosdem.org/2016/k4601/reproducible-builds-in-freebsd-packages.mp4
-  slides: https://archive.fosdem.org/2016/schedule/event/reproducible_freebsd_packages/attachments/slides/1170/export/events/attachments/reproducible_freebsd_packages/slides/1170/reproducible_builds_freebsd
-
+  slides: https://archive.fosdem.org/2016/schedule/event/reproducible_freebsd_packages/attachments/slides/1170/export/events/attachments/reproducible_freebsd_packages/slides/1170/reproducible_builds_freebsd.
 - title: Beyond Reproducible builds
   presented_by: Chris Lamb
   event:
@@ -802,7 +784,6 @@
 - title: Reproducible builds in Debian and everywhere
   presented_by: Lunar
   event:
-    url: https://2015.rmll.info/
     name: Libre Software Meeting 2015
     date: 2015-07-06
     location: Beauvais, France
@@ -813,12 +794,9 @@
 - title: Compilations reproductibles (French)
   presented_by: Lunar
   event:
-    url: https://neuros.fr/journal/pses-2015
     date: 2015-06-19
     name: PSES 2015
     location: Paris, France
-  video:
-    url: https://static.qth.fr/PSES2015/webm/PSES2015_compilations-reproductibles.webm
   slides: https://reproducible-builds.org/_lfs/presentations/2015-06-19-PSES2015.pdf
 
 - title: Stretching out for trustworthy reproducible builds