diff --git a/_define.php b/_define.php
index d792d4d..51694f5 100644
--- a/_define.php
+++ b/_define.php
@@ -10,7 +10,7 @@
  * @copyright Jean-Christian Denis
  * @copyright GPL-2.0 https://www.gnu.org/licenses/gpl-2.0.html
  */
-if (!defined('DC_RC_PATH')) {
+if (!defined('DC_RC_PATH') || is_null(dcCore::app()->auth)) {
     return null;
 }
 
@@ -22,7 +22,7 @@ $this->registerModule(
     [
         'requires'    => [['core', '2.25']],
         'permissions' => dcCore::app()->auth->makePermissions([
-            dcAuth::PERMISSION_ADMIN,
+            dcCore::app()->auth::PERMISSION_ADMIN,
         ]),
         'type'       => 'plugin',
         'support'    => 'https://github.com/JcDenis/' . basename(__DIR__),
diff --git a/src/Backend.php b/src/Backend.php
index ad09acd..93ce456 100644
--- a/src/Backend.php
+++ b/src/Backend.php
@@ -15,7 +15,6 @@ declare(strict_types=1);
 namespace Dotclear\Plugin\postslistOptions;
 
 use ArrayObject;
-use dcAuth;
 use dcCore;
 use dcNsProcess;
 use dcPostsActions;
@@ -29,10 +28,14 @@ class Backend extends dcNsProcess
 {
     public static function init(): bool
     {
-        static::$init = defined('DC_CONTEXT_ADMIN') && dcCore::app()->auth->check(
-            dcCore::app()->auth->makePermissions([dcAuth::PERMISSION_ADMIN]),
-            dcCore::app()->blog->id
-        );
+        static::$init = defined('DC_CONTEXT_ADMIN')
+            && !is_null(dcCore::app()->auth) && !is_null(dcCore::app()->blog)
+            && dcCore::app()->auth->check(
+                dcCore::app()->auth->makePermissions([
+                    dcCore::app()->auth::PERMISSION_ADMIN,
+                ]),
+                dcCore::app()->blog->id
+            );
 
         return static::$init;
     }
diff --git a/src/BackendBehaviors.php b/src/BackendBehaviors.php
index 24bfd93..6fe0f6f 100644
--- a/src/BackendBehaviors.php
+++ b/src/BackendBehaviors.php
@@ -51,6 +51,11 @@ class BackendBehaviors
 
     public static function commentsDelete(dcPostsActions $pa, ArrayObject $post): void
     {
+        //nullsafe
+        if (is_null(dcCore::app()->blog)) {
+            return;
+        }
+
         $ids = self::getPostsIds($pa);
 
         if (empty($_POST['confirmdeletecomments'])) {
@@ -108,6 +113,11 @@ class BackendBehaviors
 
     public static function trackbacksDelete(dcPostsActions $pa, ArrayObject $post): void
     {
+        //nullsafe
+        if (is_null(dcCore::app()->blog)) {
+            return;
+        }
+
         $ids = self::getPostsIds($pa);
 
         if (empty($_POST['confirmdeletetrackbacks'])) {
@@ -157,6 +167,11 @@ class BackendBehaviors
 
     private static function updPostOption(int $id, string $option, int $value): void
     {
+        //nullsafe
+        if (is_null(dcCore::app()->blog)) {
+            return;
+        }
+
         $id  = abs((int) $id);
         $cur = dcCore::app()->con->openCursor(dcCore::app()->prefix . dcBlog::POST_TABLE_NAME);
 
@@ -172,6 +187,11 @@ class BackendBehaviors
 
     private static function delPostComments(int $id, bool $tb = false): void
     {
+        //nullsafe
+        if (is_null(dcCore::app()->blog)) {
+            return;
+        }
+
         $params = [
             'no_content'        => true,
             'post_id'           => abs((int) $id),