diff --git a/app/router.js b/app/router.js
index fdef4198c..31184d06c 100644
--- a/app/router.js
+++ b/app/router.js
@@ -20,7 +20,9 @@ const Router = Ember.Router.extend({
 });
 
 Router.map(function() {
+  this.route('404');
   this.route('project', {path: '/:project'});
+
   this.route('project-version', {path: '/:project/:project_version'}, function() {
     // this.route('classes-redirect', {path: '/classes'});
 
diff --git a/app/routes/application.js b/app/routes/application.js
index afd0691a0..b98ece43a 100644
--- a/app/routes/application.js
+++ b/app/routes/application.js
@@ -5,6 +5,7 @@ const { set, inject } = Ember;
 
 export default Ember.Route.extend({
   headData: inject.service(),
+
   title(tokens) {
     const reversed = Ember.makeArray(tokens).reverse();
     const title = `${reversed.join(' - ')} - Ember API Documentation`;
@@ -12,4 +13,5 @@ export default Ember.Route.extend({
     set(this, 'headData.cdnDomain', ENV.API_HOST);
     return title;
   }
+
 });
diff --git a/app/routes/project-version/classes/class.js b/app/routes/project-version/classes/class.js
index 729349774..2f21e47b1 100644
--- a/app/routes/project-version/classes/class.js
+++ b/app/routes/project-version/classes/class.js
@@ -25,20 +25,27 @@ export default Ember.Route.extend(ScrollTracker, {
   find(typeName, param) {
     return this.store.find(typeName, param).catch(() => {
       return this.store.find('namespace', param).catch(() => {
-        return this.transitionTo('project-version'); // class doesn't exist in new version
+        return Ember.RSVP.resolve({ isError: true });
       });
     });
   },
 
+  redirect(model, transition) {
+    if (model.isError) {
+      this.transitionTo('404');
+    }
+  },
+
   afterModel(klass) {
-    set(this, 'headData.description', klass.get('ogDescription'));
-    const relationships = get(klass.constructor, 'relationshipNames');
-    const promises = Object.keys(relationships).reduce((memo, relationshipType) => {
-      const relationshipPromises = relationships[relationshipType].map(name => klass.get(name));
-      return memo.concat(relationshipPromises);
-    }, []);
-
-    return Ember.RSVP.all(promises);
+    if (!klass.isError) {
+      set(this, 'headData.description', klass.get('ogDescription'));
+      const relationships = get(klass.constructor, 'relationshipNames');
+      const promises = Object.keys(relationships).reduce((memo, relationshipType) => {
+        const relationshipPromises = relationships[relationshipType].map(name => klass.get(name));
+        return memo.concat(relationshipPromises);
+      }, []);
+      return Ember.RSVP.all(promises);
+    }
   },
 
   serialize(model) {
diff --git a/app/templates/404.hbs b/app/templates/404.hbs
new file mode 100644
index 000000000..18fc74ad1
--- /dev/null
+++ b/app/templates/404.hbs
@@ -0,0 +1,10 @@
+<article class="whoops">
+  <br><br>
+  <h2 class="whoops__title">Ack! 404 friend, you're in the wrong place</h2>
+  <div class="whoops__message">
+    <p>
+      This page wasn't found. Please try the {{#link-to 'index'}}API docs page{{/link-to}}.
+      If you expected something else to be here, please file a <a href="https://github.com/ember-learn/ember-api-docs/issues/new" target="_blank" rel="noopener">ticket</a>.
+    </p>
+  </div>
+</article>