diff --git a/Admin/Install/Navigation.php b/Admin/Install/Navigation.php
index fbba460..e36bc61 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 c8822ed..0f480e6 100644
--- a/Controller/BackendController.php
+++ b/Controller/BackendController.php
@@ -23,6 +23,7 @@ use Modules\Admin\Models\GroupPermissionMapper;
 use Modules\Admin\Models\NullAccountPermission;
 use Modules\Admin\Models\NullGroupPermission;
 
+use phpOMS\Contract\RenderableInterface;
 use phpOMS\DataStorage\Database\RelationType;
 use phpOMS\Message\RequestAbstract;
 use phpOMS\Message\ResponseAbstract;
@@ -53,11 +54,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewSettingsGeneral(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewSettingsGeneral(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view     = new View($this->app, $request, $response);
         $settings = $this->app->appSettings->get([
@@ -88,11 +89,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewEmptyCommand(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewEmptyCommand(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -108,11 +109,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewAccountList(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewAccountList(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -131,11 +132,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewAccountSettings(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewAccountSettings(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -166,11 +167,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewAccountCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewAccountCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -187,11 +188,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewGroupList(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewGroupList(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -209,11 +210,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewGroupSettings(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewGroupSettings(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -247,11 +248,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewGroupCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewGroupCreate(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -271,11 +272,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewModuleList(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewModuleList(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
@@ -291,11 +292,11 @@ final class BackendController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      */
-    public function viewModuleProfile(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewModuleProfile(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
diff --git a/Controller/ConsoleController.php b/Controller/ConsoleController.php
index d9d9d5a..38b9d09 100644
--- a/Controller/ConsoleController.php
+++ b/Controller/ConsoleController.php
@@ -14,6 +14,7 @@ declare(strict_types=1);
 
 namespace Modules\Admin\Controller;
 
+use phpOMS\Contract\RenderableInterface;
 use phpOMS\Message\RequestAbstract;
 use phpOMS\Message\ResponseAbstract;
 use phpOMS\Views\View;
@@ -40,12 +41,12 @@ final class ConsoleController extends Controller
      * @param ResponseAbstract $response Response
      * @param mixed            $data     Generic data
      *
-     * @return \Serializable Serializable web view
+     * @return RenderableInterface Response can be rendered
      *
      * @since  1.0.0
      * @codeCoverageIgnore
      */
-    public function viewEmptyCommand(RequestAbstract $request, ResponseAbstract $response, $data = null) : \Serializable
+    public function viewEmptyCommand(RequestAbstract $request, ResponseAbstract $response, $data = null) : RenderableInterface
     {
         $view = new View($this->app, $request, $response);
 
diff --git a/Models/AccountMapper.php b/Models/AccountMapper.php
index 68f6df8..c768b1b 100644
--- a/Models/AccountMapper.php
+++ b/Models/AccountMapper.php
@@ -53,12 +53,12 @@ final class AccountMapper extends DataMapperAbstract
     /**
      * Has many relation.
      *
-     * @var array<string, array<string, string>>
+     * @var array<string, array<string, null|string>>
      * @since 1.0.0
      */    /**
      * Has many relation.
      *
-     * @var array<string, array<string, string>>
+     * @var array<string, array<string, null|string>>
      * @since 1.0.0
      */
     protected static $hasMany = [
diff --git a/Models/GroupMapper.php b/Models/GroupMapper.php
index 0d9aa86..a4867d6 100644
--- a/Models/GroupMapper.php
+++ b/Models/GroupMapper.php
@@ -69,12 +69,12 @@ final class GroupMapper extends DataMapperAbstract
     /**
      * Has many relation.
      *
-     * @var array<string, array<string, string>>
+     * @var array<string, array<string, null|string>>
      * @since 1.0.0
      */    /**
      * Has many relation.
      *
-     * @var array<string, array<string, string>>
+     * @var array<string, array<string, null|string>>
      * @since 1.0.0
      */
     protected static $hasMany = [