1 files changed, 43 insertions, 0 deletions
diff --git a/nixos/doc/manual/release-notes/rl-1909.xml b/nixos/doc/manual/release-notes/rl-1909.xml
index cc0d97023f96..2cfaec49c02e 100644
--- a/nixos/doc/manual/release-notes/rl-1909.xml
+++ b/nixos/doc/manual/release-notes/rl-1909.xml
@@ -46,6 +46,39 @@
          xmlns:xlink="http://www.w3.org/1999/xlink"
          xmlns:xi="http://www.w3.org/2001/XInclude"
          version="5.0"
+         xml:id="sec-release-19.09-incompatibilities">
+  <title>Backward Incompatibilities</title>
+
+  <para>
+   When upgrading from a previous release, please be aware of the following
+   incompatible changes:
+  </para>
+
+  <itemizedlist>
+   <listitem>
+    <para>
+     Buildbot no longer supports Python 2, as support was dropped upstream in
+     version 2.0.0. Configurations may need to be modified to make them
+     compatible with Python 3.
+    </para>
+   </listitem>
+   <listitem>
+    <para>
+     PostgreSQL now uses
+     <filename class="directory">/run/postgresql</filename> as its socket
+     directory instead of <filename class="directory">/tmp</filename>. So
+     if you run an application like eg. Nextcloud, where you need to use
+     the Unix socket path as the database host name, you need to change it
+     accordingly.
+    </para>
+   </listitem>
+  </itemizedlist>
+ </section>
+
+ <section xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xmlns:xi="http://www.w3.org/2001/XInclude"
+         version="5.0"
          xml:id="sec-release-19.09-notable-changes">
   <title>Other Notable Changes</title>
 
@@ -66,6 +99,16 @@
      and fix all the bugs it uncovers.
     </para>
    </listitem>
+   <listitem>
+    <para>
+     The <literal>vlc</literal> package gained support for Chromecast
+     streaming, enabled by default. TCP port 8010 must be open for it to work,
+     so something like <literal>networking.firewall.allowedTCPPorts = [ 8010
+     ];</literal> may be required in your configuration. Also consider enabling
+     <link xlink:href="https://nixos.wiki/wiki/Accelerated_Video_Playback">
+     Accelerated Video Playback</link> for better transcoding performance.
+    </para>
+   </listitem>
   </itemizedlist>
  </section>
 </section>