diff --git a/src/Alias.php b/src/Alias.php
index 63c3fca..38c9d3d 100644
--- a/src/Alias.php
+++ b/src/Alias.php
@@ -40,6 +40,11 @@ class Alias
             return $this->aliases;
         }
 
+        // nullsafe PHP < 8.0
+        if (is_null(dcCore::app()->blog)) {
+            return [];
+        }
+
         $sql = new SelectStatement();
         $rs  = $sql->from(dcCore::app()->prefix . My::ALIAS_TABLE_NAME)
             ->columns([
@@ -97,6 +102,11 @@ class Alias
      */
     public function createAlias(string $url, string $destination, int $position): void
     {
+        // nullsafe PHP < 8.0
+        if (is_null(dcCore::app()->blog)) {
+            return;
+        }
+
         $url         = trim($url);
         $destination = trim($destination);
 
@@ -122,6 +132,11 @@ class Alias
      */
     public function deleteAlias(string $url): void
     {
+        // nullsafe PHP < 8.0
+        if (is_null(dcCore::app()->blog)) {
+            return;
+        }
+
         $sql = new DeleteStatement();
         $sql->from(dcCore::app()->prefix . My::ALIAS_TABLE_NAME)
             ->where('blog_id = ' . $sql->quote((string) dcCore::app()->blog->id))
@@ -134,6 +149,11 @@ class Alias
      */
     public function deleteAliases(): void
     {
+        // nullsafe PHP < 8.0
+        if (is_null(dcCore::app()->blog)) {
+            return;
+        }
+
         $sql = new DeleteStatement();
         $sql->from(dcCore::app()->prefix . My::ALIAS_TABLE_NAME)
             ->where('blog_id = ' . $sql->quote((string) dcCore::app()->blog->id))
diff --git a/src/Backend.php b/src/Backend.php
index 6636081..3182444 100644
--- a/src/Backend.php
+++ b/src/Backend.php
@@ -27,6 +27,7 @@ class Backend extends dcNsProcess
     public static function init(): bool
     {
         static::$init = defined('DC_CONTEXT_ADMIN')
+            && !is_null(dcCore::app()->auth) && !is_null(dcCore::app()->blog) //nullsafe PHP < 8.0
             && dcCore::app()->auth->check(dcCore::app()->auth->makePermissions([
                 dcCore::app()->auth::PERMISSION_ADMIN,
             ]), dcCore::app()->blog->id);
@@ -40,6 +41,11 @@ class Backend extends dcNsProcess
             return false;
         }
 
+        // nullsafe PHP < 8.0
+        if (is_null(dcCore::app()->auth) || is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl)) {
+            return false;
+        }
+
         dcCore::app()->menu[dcAdmin::MENU_PLUGINS]->addItem(
             My::name(),
             dcCore::app()->adminurl->get('admin.plugin.' . My::id()),
diff --git a/src/Manage.php b/src/Manage.php
index 4dccc80..e321379 100644
--- a/src/Manage.php
+++ b/src/Manage.php
@@ -40,12 +40,10 @@ class Manage extends dcNsProcess
     public static function init(): bool
     {
         static::$init = defined('DC_CONTEXT_ADMIN')
-            && dcCore::app()->auth->check(
-                dcCore::app()->auth->makePermissions([
-                    dcCore::app()->auth::PERMISSION_ADMIN,
-                ]),
-                dcCore::app()->blog->id
-            );
+            && !is_null(dcCore::app()->auth) && !is_null(dcCore::app()->blog) //nullsafe PHP < 8.0
+            && dcCore::app()->auth->check(dcCore::app()->auth->makePermissions([
+                dcCore::app()->auth::PERMISSION_ADMIN,
+            ]), dcCore::app()->blog->id);
 
         return static::$init;
     }
@@ -56,6 +54,11 @@ class Manage extends dcNsProcess
             return false;
         }
 
+        // nullsafe PHP < 8.0
+        if (is_null(dcCore::app()->auth) || is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl)) {
+            return false;
+        }
+
         if (empty($_POST) || empty($_POST['a']) && empty($_POST['alias_url'])) {
             return true;
         }
@@ -94,6 +97,11 @@ class Manage extends dcNsProcess
             return;
         }
 
+        // nullsafe PHP < 8.0
+        if (is_null(dcCore::app()->blog) || is_null(dcCore::app()->adminurl)) {
+            return;
+        }
+
         $alias   = new Alias();
         $aliases = $alias->getAliases();