diff --git a/src/Backend.php b/src/Backend.php
index 211bb93..24bf31f 100644
--- a/src/Backend.php
+++ b/src/Backend.php
@@ -14,7 +14,6 @@ declare(strict_types=1);
 
 namespace Dotclear\Plugin\httpPassword;
 
-use dcAuth;
 use dcAdmin;
 use dcCore;
 use dcPage;
@@ -31,10 +30,11 @@ class Backend extends dcNsProcess
 
     public static function process(): bool
     {
-        if (!static::$init) {
+        if (!static::$init || is_null(dcCore::app()->auth) || is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl)) {
             return false;
         }
 
+        // add backend sidebar menu icon
         dcCore::app()->menu[dcAdmin::MENU_PLUGINS]->addItem(
             My::name(),
             dcCore::app()->adminurl->get('admin.plugin.' . My::id()),
diff --git a/src/Frontend.php b/src/Frontend.php
index 9936da4..57d07ab 100644
--- a/src/Frontend.php
+++ b/src/Frontend.php
@@ -33,7 +33,12 @@ class Frontend extends dcNsProcess
             return false;
         }
 
+        // check password on frontend
         dcCore::app()->addBehavior('publicPrependV2', function (): void {
+            // nullsafe
+            if (is_null(dcCore::app()->blog)) {
+                return;
+            }
             $PHP_AUTH_USER = $PHP_AUTH_PW = '';
 
             if (isset($_SERVER['PHP_AUTH_USER']) and isset($_SERVER['PHP_AUTH_PW'])) {
diff --git a/src/Install.php b/src/Install.php
index f8774f6..cd47085 100644
--- a/src/Install.php
+++ b/src/Install.php
@@ -22,14 +22,15 @@ class Install extends dcNsProcess
 {
     public static function init(): bool
     {
-        static::$init = defined('DC_CONTEXT_ADMIN') && dcCore::app()->newVersion(My::id(), dcCore::app()->plugins->moduleInfo(My::id(), 'version'));
+        static::$init = defined('DC_CONTEXT_ADMIN')
+            && dcCore::app()->newVersion(My::id(), dcCore::app()->plugins->moduleInfo(My::id(), 'version'));
 
         return static::$init;
     }
 
     public static function process(): bool
     {
-        if (!static::$init) {
+        if (!static::$init || is_null(dcCore::app()->blog)) {
             return false;
         }
 
diff --git a/src/Manage.php b/src/Manage.php
index 4e57fff..3186d54 100644
--- a/src/Manage.php
+++ b/src/Manage.php
@@ -40,18 +40,21 @@ class Manage extends dcNsProcess
 {
     public static function init(): bool
     {
-        static::$init = defined('DC_CONTEXT_ADMIN') && dcCore::app()->auth->check(
-            dcCore::app()->auth->makePermissions([
-                My::PERMISSION,
-            ]), dcCore::app()->blog->id
-        );
+        static::$init = defined('DC_CONTEXT_ADMIN')
+            && !is_null(dcCore::app()->auth) && !is_null(dcCore::app()->blog) // nullsafe
+            && dcCore::app()->auth->check(
+                dcCore::app()->auth->makePermissions([
+                    My::PERMISSION,
+                ]),
+                dcCore::app()->blog->id
+            );
 
         return static::$init;
     }
 
     public static function process(): bool
     {
-        if (!static::$init) {
+        if (!static::$init || is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl)) {
             return false;
         }
 
@@ -67,6 +70,7 @@ class Manage extends dcNsProcess
             return true;
         }
 
+        // save settings
         if ('savesettings' == $action) {
             $s = dcCore::app()->blog->settings->get(My::id());
             $s->put('active', !empty($_POST['active']));
@@ -85,6 +89,7 @@ class Manage extends dcNsProcess
             );
         }
 
+        // delete users logins
         if ('savelogins' == $action) {
             $logs = dcCore::app()->log->getLogs(['log_table' => My::id()]);
             if (!$logs->isEmpty()) {
@@ -105,6 +110,7 @@ class Manage extends dcNsProcess
             }
         }
 
+        // save users logins / passwords in frontend passwords file
         if ('savepasswords' == $action) {
             $passwords = self::getPasswords();
             $lines     = [];
@@ -153,7 +159,7 @@ class Manage extends dcNsProcess
 
     public static function render(): void
     {
-        if (!static::$init) {
+        if (!static::$init || is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl)) {
             return;
         }
 
@@ -173,7 +179,7 @@ class Manage extends dcNsProcess
         ]) .
         dcPage::notices() .
 
-        # Filters select menu list
+        // Filters select menu list
         (new Form('section_menu'))->action(dcCore::app()->adminurl->get('admin.plugin.' . My::id()))->method('get')->fields([
             (new Para())->class('anchor-nav')->items([
                 (new Label(__('Select section:')))->for('part')->class('classic'),
@@ -185,6 +191,7 @@ class Manage extends dcNsProcess
 
         '<h3>' . array_search($part, My::sectionCombo()) . '</h3>';
 
+        // settigns form
         if ('settings' == $part) {
             echo
             (new Form('section_settings'))->action(dcCore::app()->adminurl->get('admin.plugin.' . My::id(), ['part' => 'settings']))->method('post')->fields([
@@ -214,6 +221,7 @@ class Manage extends dcNsProcess
             ])->render();
         }
 
+        // delete logins form
         if ('logins' == $part) {
             $logs = dcCore::app()->log->getLogs(['log_table' => My::id()]);
             if ($logs->isEmpty()) {
@@ -250,6 +258,7 @@ class Manage extends dcNsProcess
             }
         }
 
+        // existing logins/passwords form
         if ('passwords' == $part) {
             $passwords = self::getPasswords();
 
@@ -295,6 +304,7 @@ class Manage extends dcNsProcess
                 ])->render();
             }
 
+            // new login form
             echo
             (new Form('section_new'))->action(dcCore::app()->adminurl->get('admin.plugin.' . My::id(), ['part' => $part]))->method('post')->fields([
                 (new Text('h3', Html::escapeHTML(__('Add a user')))),
@@ -320,6 +330,11 @@ class Manage extends dcNsProcess
         dcPage::closeModule();
     }
 
+    /**
+     * Get page section.
+     *
+     * @return  string  The section
+     */
     private static function getSection(): string
     {
         $part = $_REQUEST['part'] ?? 'settings';
@@ -330,6 +345,11 @@ class Manage extends dcNsProcess
         return $part;
     }
 
+    /**
+     * Get existing passwords from file.
+     *
+     * @return  array<string,string>    The passwords list
+     */
     private static function getPasswords(): array
     {
         $passwords = [];
diff --git a/src/Prepend.php b/src/Prepend.php
index 1979625..6fc4430 100644
--- a/src/Prepend.php
+++ b/src/Prepend.php
@@ -28,10 +28,11 @@ class Prepend extends dcNsProcess
 
     public static function process(): bool
     {
-        if (!static::$init) {
+        if (!static::$init || is_null(dcCore::app()->auth)) {
             return false;
         }
 
+        // register module permission
         dcCore::app()->auth->setPermissionType(
             My::PERMISSION,
             __('Manage http password blog protection')
diff --git a/src/Utils.php b/src/Utils.php
index 716c5b3..9c7af5b 100644
--- a/src/Utils.php
+++ b/src/Utils.php
@@ -20,9 +20,15 @@ class Utils
 {
     /**
      * Crypt password
+     *
+     * @param   string  $secret     The secret
+     *
+     * @return  string  The crypt password (empty on error)
      */
     public static function crypt(?string $secret): string
     {
+        $secret = (string) $secret;
+
         switch (self::cryptMethod()) {
             case 'plaintext':
                 $saltlen = -1;
@@ -72,43 +78,53 @@ class Utils
             $secret = crypt($secret, $salt);
         }
 
-        return($secret);
+        return $secret;
     }
 
     /**
      * Setting: active
+     *
+     * @return  bool    True if module is active
      */
     public static function isActive(): bool
     {
-        return (bool) dcCore::app()->blog->settings->get(My::id())->get('active');
+        return !is_null(dcCore::app()->blog) && (bool) dcCore::app()->blog->settings->get(My::id())->get('active');
     }
 
     /**
      * Setting: crypt
+     *
+     * @return  string  The crypt method
      */
     public static function cryptMethod(): string
     {
-        return (string) dcCore::app()->blog->settings->get(My::id())->get('crypt');
+        return is_null(dcCore::app()->blog) ? '' : (string) dcCore::app()->blog->settings->get(My::id())->get('crypt');
     }
 
     /**
      * Setting: message
+     *
+     * @return  string  The frontend message
      */
     public static function httpMessage(): string
     {
-        return (string) dcCore::app()->blog->settings->get(My::id())->get('message');
+        return is_null(dcCore::app()->blog) ? '' : (string) dcCore::app()->blog->settings->get(My::id())->get('message');
     }
 
     /**
      * Get passwords file path
+     *
+     * @return  string  The passwords file path (empty on error)
      */
     public static function passwordFile(): string
     {
-        return dcCore::app()->blog->public_path . DIRECTORY_SEPARATOR . My::FILE_PASSWORD;
+        return is_null(dcCore::app()->blog) ? '' : dcCore::app()->blog->public_path . DIRECTORY_SEPARATOR . My::FILE_PASSWORD;
     }
 
     /**
      * Check passwords file
+     *
+     * @return  bool    True if passwords file is writable
      */
     public static function isWritable(): bool
     {