diff --git a/user_guide_src/source/installation/upgrade_404.rst b/user_guide_src/source/installation/upgrade_404.rst
new file mode 100644
index 000000000000..8703e3bd6680
--- /dev/null
+++ b/user_guide_src/source/installation/upgrade_404.rst
@@ -0,0 +1,20 @@
+#############################
+Upgrading from 4.0.x to 4.0.4
+#############################
+
+CodeIgniter 4.0.4 fixes a bug in the implementation of :doc:`Controller Filters </incoming/filters>`, breaking
+code implementing the ``FilterInterface``.
+
+**Update FilterInterface declarations**
+
+The method signatures for ``after()`` and ``before()`` must be updated to include ``$arguments``. The function
+definitions should be changed from::
+
+    public function before(RequestInterface $request)
+    public function after(RequestInterface $request, ResponseInterface $response)
+
+to::
+
+    public function before(RequestInterface $request, $arguments = null)
+    public function after(RequestInterface $request, ResponseInterface $response, $arguments = null)
+
diff --git a/user_guide_src/source/installation/upgrading.rst b/user_guide_src/source/installation/upgrading.rst
index c271e0c90dea..1e0e8121edc4 100644
--- a/user_guide_src/source/installation/upgrading.rst
+++ b/user_guide_src/source/installation/upgrading.rst
@@ -6,6 +6,7 @@ Please read the upgrade notes corresponding to the version you are
 upgrading from.
 
 .. toctree::
-	:titlesonly:
+    :titlesonly:
 
-	Upgrading from 3.x to 4.x <upgrade_4xx>
\ No newline at end of file
+    Upgrading from 4.0.x to 4.0.4 <upgrade_404>
+	Upgrading from 3.x to 4.x <upgrade_4xx>