diff --git a/Admin/Install/Navigation.php b/Admin/Install/Navigation.php
index 8163056..d6564b1 100644
--- a/Admin/Install/Navigation.php
+++ b/Admin/Install/Navigation.php
@@ -36,7 +36,7 @@ class Navigation
      *
      * @since  1.0.0
      */
-    public static function install(string $path = null, DatabasePool $dbPool = null) : void
+    public static function install(string $path, DatabasePool $dbPool) : void
     {
         \Modules\Navigation\Admin\Installer::installExternal($dbPool, ['path' => __DIR__ . '/Navigation.install.json']);
     }
diff --git a/Controller/BackendController.php b/Controller/BackendController.php
index 1575ac8..5a9f71f 100644
--- a/Controller/BackendController.php
+++ b/Controller/BackendController.php
@@ -18,6 +18,7 @@ use Modules\Organization\Models\DepartmentMapper;
 use Modules\Organization\Models\PositionMapper;
 use Modules\Organization\Models\UnitMapper;
 
+use phpOMS\Contract\RenderableInterface;
 use phpOMS\Message\RequestAbstract;
 use phpOMS\Message\ResponseAbstract;
 use phpOMS\Views\View;
@@ -38,12 +39,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewUnitList(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewUnitList(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -60,12 +61,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewUnitProfile(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewUnitProfile(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -88,12 +89,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewUnitCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewUnitCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -114,12 +115,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewDepartmentList(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewDepartmentList(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -136,12 +137,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewDepartmentProfile(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewDepartmentProfile(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -167,12 +168,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewDepartmentCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewDepartmentCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -196,12 +197,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewPositionList(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewPositionList(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -218,12 +219,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewPositionProfile(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewPositionProfile(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -249,12 +250,12 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable
+     * @return RenderableInterface
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewPositionCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewPositionCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);