diff --git a/src/Backend.php b/src/Backend.php
index 22417d2..3d7117a 100644
--- a/src/Backend.php
+++ b/src/Backend.php
@@ -15,7 +15,6 @@ declare(strict_types=1);
 namespace Dotclear\Plugin\filesAlias;
 
 use dcAdmin;
-use dcAuth;
 use dcCore;
 use dcFavorites;
 use dcNsProcess;
@@ -36,23 +35,32 @@ class Backend extends dcNsProcess
             return false;
         }
 
+        // nullsafe
+        if (is_null(dcCore::app()->auth) || is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl)) {
+            return false;
+        }
+
         dcCore::app()->menu[dcAdmin::MENU_BLOG]->addItem(
             My::name(),
             dcCore::app()->adminurl->get('admin.plugin.' . My::id()),
             dcPage::getPF(My::id() . '/icon.svg'),
             preg_match('/' . preg_quote(dcCore::app()->adminurl->get('admin.plugin.' . My::id())) . '(&.*)?$/', $_SERVER['REQUEST_URI']),
-            dcCore::app()->auth->check(dcCore::app()->auth->makePermissions([dcAuth::PERMISSION_CONTENT_ADMIN]), dcCore::app()->blog->id)
+            dcCore::app()->auth->check(dcCore::app()->auth->makePermissions([dcCore::app()->auth::PERMISSION_CONTENT_ADMIN]), dcCore::app()->blog->id)
         );
 
         dcCore::app()->addBehavior('adminDashboardFavoritesV2', function (dcFavorites $favs): void {
+            // nullsafe
+            if (is_null(dcCore::app()->auth) || is_null(dcCore::app()->adminurl)) {
+                return;
+            }
             $favs->register(My::id(), [
                 'title'       => My::name(),
                 'url'         => dcCore::app()->adminurl->get('admin.plugin.' . My::id()),
                 'small-icon'  => dcPage::getPF(My::id() . '/icon.svg'),
                 'large-icon'  => dcPage::getPF(My::id() . '/icon.svg'),
                 'permissions' => dcCore::app()->auth->makePermissions([
-                    dcAuth::PERMISSION_USAGE,
-                    dcAuth::PERMISSION_CONTENT_ADMIN,
+                    dcCore::app()->auth::PERMISSION_USAGE,
+                    dcCore::app()->auth::PERMISSION_CONTENT_ADMIN,
                 ]),
             ]);
         });
diff --git a/src/Manage.php b/src/Manage.php
index a4a5b1d..08299a9 100644
--- a/src/Manage.php
+++ b/src/Manage.php
@@ -14,7 +14,6 @@ declare(strict_types=1);
 
 namespace Dotclear\Plugin\filesAlias;
 
-use dcAuth;
 use dcCore;
 use dcMedia;
 use dcNsProcess;
@@ -37,12 +36,14 @@ class Manage 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) // nullsafe
+            && dcCore::app()->auth->check(
+                dcCore::app()->auth->makePermissions([
+                    dcCore::app()->auth::PERMISSION_ADMIN,
+                ]),
+                dcCore::app()->blog->id
+            );
 
         return static::$init;
     }
@@ -53,11 +54,16 @@ class Manage extends dcNsProcess
             return false;
         }
 
+        // nullsafe
+        if (is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl)) {
+            return false;
+        }
+
         if (!(dcCore::app()->media instanceof dcMedia)) {
             dcCore::app()->media = new dcMedia();
         }
 
-        # Update aliases
+        // Update aliases
         if (isset($_POST['a']) && is_array($_POST['a'])) {
             try {
                 Utils::updateAliases($_POST['a']);
@@ -68,7 +74,7 @@ class Manage extends dcNsProcess
             }
         }
 
-        # New alias
+        // New alias
         if (isset($_POST['filesalias_url'])) {
             $url = empty($_POST['filesalias_url']) ? PallazzoTools::rand_uniqid() : $_POST['filesalias_url'];
 
@@ -132,6 +138,11 @@ class Manage extends dcNsProcess
 
     private static function displayAliasForm(): void
     {
+        // nullsafe
+        if (is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl) || is_null(dcCore::app()->media)) {
+            return;
+        }
+
         echo
         dcPage::breadcrumb([
             Html::escapeHTML(dcCore::app()->blog->name) => '',
@@ -175,6 +186,11 @@ class Manage extends dcNsProcess
 
     private static function displayAliasList(): void
     {
+        // nullsafe
+        if (is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl) || is_null(dcCore::app()->media)) {
+            return;
+        }
+
         $aliases = Utils::getAliases();
 
         echo
diff --git a/src/UrlHandler.php b/src/UrlHandler.php
index 914335b..d682f66 100644
--- a/src/UrlHandler.php
+++ b/src/UrlHandler.php
@@ -22,6 +22,11 @@ class UrlHandler extends dcUrlHandlers
 {
     public static function alias(string $args): void
     {
+        // nullsafe
+        if (is_null(dcCore::app()->ctx)) {
+            return;
+        }
+
         $delete = false;
 
         dcCore::app()->ctx->__set('filealias', Utils::getAlias($args));
diff --git a/src/Utils.php b/src/Utils.php
index f68d67f..a62d194 100644
--- a/src/Utils.php
+++ b/src/Utils.php
@@ -23,20 +23,26 @@ class Utils
 {
     public static function getAliases(): dcRecord
     {
+        // nullsafe
+        $blog_id = is_null(dcCore::app()->blog) ? '' : dcCore::app()->blog->id;
+
         return new dcRecord(dcCore::app()->con->select(
             'SELECT filesalias_url, filesalias_destination, filesalias_password, filesalias_disposable ' .
             'FROM ' . dcCore::app()->prefix . My::ALIAS_TABLE_NAME . ' ' .
-            "WHERE blog_id = '" . dcCore::app()->con->escapeStr(dcCore::app()->blog->id) . "' " .
+            "WHERE blog_id = '" . dcCore::app()->con->escapeStr($blog_id) . "' " .
             'ORDER BY filesalias_url ASC '
         ));
     }
 
     public static function getAlias(string $url): dcRecord
     {
+        // nullsafe
+        $blog_id = is_null(dcCore::app()->blog) ? '' : dcCore::app()->blog->id;
+
         return new dcRecord(dcCore::app()->con->select(
             'SELECT filesalias_url, filesalias_destination, filesalias_password, filesalias_disposable ' .
             'FROM ' . dcCore::app()->prefix . My::ALIAS_TABLE_NAME . ' ' .
-            "WHERE blog_id = '" . dcCore::app()->con->escapeStr(dcCore::app()->blog->id) . "' " .
+            "WHERE blog_id = '" . dcCore::app()->con->escapeStr($blog_id) . "' " .
             "AND filesalias_url = '" . dcCore::app()->con->escapeStr($url) . "' " .
             'ORDER BY filesalias_url ASC '
         ));
@@ -73,8 +79,11 @@ class Utils
             throw new Exception(__('File destination is empty.'));
         }
 
+        // nullsafe
+        $blog_id = is_null(dcCore::app()->blog) ? '' : dcCore::app()->blog->id;
+
         $cur = dcCore::app()->con->openCursor(dcCore::app()->prefix . My::ALIAS_TABLE_NAME);
-        $cur->setField('blog_id', (string) dcCore::app()->blog->id);
+        $cur->setField('blog_id', $blog_id);
         $cur->setField('filesalias_url', (string) $url);
         $cur->setField('filesalias_destination', (string) $destination);
         $cur->setField('filesalias_password', $password);
@@ -84,23 +93,34 @@ class Utils
 
     public static function deleteAliases(): void
     {
+        // nullsafe
+        $blog_id = is_null(dcCore::app()->blog) ? '' : dcCore::app()->blog->id;
+
         dcCore::app()->con->execute(
             'DELETE FROM ' . dcCore::app()->prefix . My::ALIAS_TABLE_NAME . ' ' .
-            "WHERE blog_id = '" . dcCore::app()->con->escapeStr(dcCore::app()->blog->id) . "' "
+            "WHERE blog_id = '" . dcCore::app()->con->escapeStr($blog_id) . "' "
         );
     }
 
     public static function deleteAlias(string $url): void
     {
+        // nullsafe
+        $blog_id = is_null(dcCore::app()->blog) ? '' : dcCore::app()->blog->id;
+
         dcCore::app()->con->execute(
             'DELETE FROM ' . dcCore::app()->prefix . My::ALIAS_TABLE_NAME . ' ' .
-            "WHERE blog_id = '" . dcCore::app()->con->escapeStr(dcCore::app()->blog->id) . "' " .
+            "WHERE blog_id = '" . dcCore::app()->con->escapeStr($blog_id) . "' " .
             "AND filesalias_url = '" . dcCore::app()->con->escapeStr($url) . "' "
         );
     }
 
     public static function getMediaId(string $target): int
     {
+        // nullsafe
+        if (is_null(dcCore::app()->blog)) {
+            return 0;
+        }
+
         $strReq = 'SELECT media_id ' .
         'FROM ' . dcCore::app()->prefix . dcMedia::MEDIA_TABLE_NAME . ' ' .
         "WHERE media_path = '" . dcCore::app()->con->escapeStr((string) dcCore::app()->blog->settings->get('system')->get('public_path')) . "' " .