diff --git a/nixos/doc/manual/from_md/release-notes/rl-2111.section.xml b/nixos/doc/manual/from_md/release-notes/rl-2111.section.xml
index 276408753a73..f56cd23c2ce2 100644
--- a/nixos/doc/manual/from_md/release-notes/rl-2111.section.xml
+++ b/nixos/doc/manual/from_md/release-notes/rl-2111.section.xml
@@ -881,6 +881,14 @@ Superuser created successfully.
           <literal>exfat</literal>.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          The <literal>todoman</literal> package was upgraded from 3.9.0
+          to 4.0.0. This introduces breaking changes in the
+          <link xlink:href="https://todoman.readthedocs.io/en/stable/configure.html#configuration-file">configuration
+          file</link> format.
+        </para>
+      </listitem>
     </itemizedlist>
   </section>
   <section xml:id="sec-release-21.11-notable-changes">
diff --git a/nixos/doc/manual/release-notes/rl-2111.section.md b/nixos/doc/manual/release-notes/rl-2111.section.md
index 1dbb82527fb1..616b3abae29f 100644
--- a/nixos/doc/manual/release-notes/rl-2111.section.md
+++ b/nixos/doc/manual/release-notes/rl-2111.section.md
@@ -255,6 +255,8 @@ To be able to access the web UI this port needs to be opened in the firewall.
 - If `exfat` is included in `boot.supportedFilesystems` and when using kernel 5.7
   or later, the `exfatprogs` user-space utilities are used instead of `exfat`.
 
+- The `todoman` package was upgraded from 3.9.0 to 4.0.0. This introduces breaking changes in the [configuration file](https://todoman.readthedocs.io/en/stable/configure.html#configuration-file) format.
+
 ## Other Notable Changes {#sec-release-21.11-notable-changes}
 
 - The setting [`services.openssh.logLevel`](options.html#opt-services.openssh.logLevel) `"VERBOSE"` `"INFO"`. This brings NixOS in line with upstream and other Linux distributions, and reduces log spam on servers due to bruteforcing botnets.
diff --git a/pkgs/applications/office/todoman/default.nix b/pkgs/applications/office/todoman/default.nix
index fc9f70094da1..e01391519e49 100644
--- a/pkgs/applications/office/todoman/default.nix
+++ b/pkgs/applications/office/todoman/default.nix
@@ -10,11 +10,11 @@ let
 in
 buildPythonApplication rec {
   pname = "todoman";
-  version = "3.9.0";
+  version = "4.0.0";
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "e7e5cab13ecce0562b1f13f46ab8cbc079caed4b462f2371929f8a4abff2bcbe";
+    sha256 = "4c4d0c6533da8d553f3dd170c9c4ff3752eb11fd7177ee391414a39adfef60ad";
   };
 
   SETUPTOOLS_SCM_PRETEND_VERSION = version;
@@ -28,7 +28,6 @@ buildPythonApplication rec {
     click
     click-log
     click-repl
-    configobj
     humanize
     icalendar
     parsedatetime