diff --git a/docs/upgrade-guides/2-21-0-to-3-0-0.md b/docs/upgrade-guides/2-21-0-to-3-0-0.md
new file mode 100644
index 0000000..a1db2b5
--- /dev/null
+++ b/docs/upgrade-guides/2-21-0-to-3-0-0.md
@@ -0,0 +1,6 @@
+# 2.21.0 to 3.0.0
+
+No special instructions are necessary to upgrade to `v3.0.0`.
+
+Aerie `v3.0.0` includes a new feature to support uploading and visualizing External Events, see the [External Events](https://nasa-ammos.github.io/aerie-docs/planning/external-events/) docs page for more information.
+
diff --git a/sidebars.js b/sidebars.js
index 828fbf2..d337ef4 100644
--- a/sidebars.js
+++ b/sidebars.js
@@ -435,6 +435,7 @@ const sidebars = {
     },
   ],
   upgradeGuides: [
+    'upgrade-guides/2-21-0-to-3-0-0',
     'upgrade-guides/2-20-0-to-2-21-0',
     'upgrade-guides/2-19-0-to-2-20-0',
     'upgrade-guides/2-18-0-to-2-19-0',
diff --git a/static/mgss-cover-page.html b/static/mgss-cover-page.html
index ec325b2..14e9b5b 100644
--- a/static/mgss-cover-page.html
+++ b/static/mgss-cover-page.html
@@ -35,7 +35,7 @@ <h2>Identification</h2>
               <td>636.101</td>
               <td>MPSA</td>
               <td>Aerie</td>
-              <td id="aerie-version">2.21.0</td>
+              <td id="aerie-version">3.0.0</td>
             </tr>
           </tbody>
         </table>