diff --git a/app/utils/ember-versions.js b/app/utils/ember-versions.js
index 812818d..8274a9f 100644
--- a/app/utils/ember-versions.js
+++ b/app/utils/ember-versions.js
@@ -104,4 +104,5 @@ export const VERSIONS = Object.freeze([
   '5.6',
   '5.7',
   '5.8',
+  '5.9',
 ]);
diff --git a/source/ember-cli-changes/5.9.md b/source/ember-cli-changes/5.9.md
new file mode 100644
index 0000000..e062d06
--- /dev/null
+++ b/source/ember-cli-changes/5.9.md
@@ -0,0 +1,10 @@
+---
+version: '5.9'
+changes:
+  - feature: true
+    title: 'Format markdown files in blueprints with Prettier.'
+    link: 'https://blog.emberjs.com/ember-released-5-9'
+  - feature: true
+    title: 'Remove warning when encountering a `.js` file when generating a `TS` blueprint.'
+    link: 'https://blog.emberjs.com/ember-released-5-9'
+---
diff --git a/source/ember-js-changes/5.9.md b/source/ember-js-changes/5.9.md
new file mode 100644
index 0000000..6cbd08c
--- /dev/null
+++ b/source/ember-js-changes/5.9.md
@@ -0,0 +1,10 @@
+---
+version: '5.9'
+changes:
+  - deprecation: true
+    title: 'Deprecate `(action)` and `{{action}}` in templates per RFC #1006.'
+    link: 'https://blog.emberjs.com/ember-released-5-9'
+  - feature: true
+    title: 'Make deprecations throw when the until for `ember-source` has passed per RFC #0830.'
+    link: 'https://blog.emberjs.com/ember-released-5-9'
+---
diff --git a/tests/acceptance/changes-test.js b/tests/acceptance/changes-test.js
index 849d821..b2aad7c 100644
--- a/tests/acceptance/changes-test.js
+++ b/tests/acceptance/changes-test.js
@@ -16,8 +16,8 @@ module('Acceptance | changes', function (hooks) {
 
     assert.strictEqual(
       newFeaturesInEmberJS.length,
-      42,
-      'We see 42 new features that occurred in Ember.js since version 3.15'
+      43,
+      'We see 43 new features that occurred in Ember.js since version 3.15'
     );
 
     // Check deprecations in Ember.js
@@ -27,8 +27,8 @@ module('Acceptance | changes', function (hooks) {
 
     assert.strictEqual(
       deprecationsInEmberJS.length,
-      30,
-      'We see 30 deprecations that occurred in Ember.js since version 3.15'
+      31,
+      'We see 31 deprecations that occurred in Ember.js since version 3.15'
     );
 
     // Check new features in Ember Data
@@ -60,8 +60,8 @@ module('Acceptance | changes', function (hooks) {
 
     assert.strictEqual(
       newFeaturesInEmberCLI.length,
-      71,
-      'We see 71 new features that occurred in Ember CLI since version 3.15'
+      73,
+      'We see 73 new features that occurred in Ember CLI since version 3.15'
     );
 
     // Check deprecations in Ember CLI