diff --git a/lib/classes/Seminar.class.php b/lib/classes/Seminar.class.php
index 12e44249b271a6870227f31a98ddf3594442f554..054c337d4a1323f87bed7789511531b3f4202e0c 100644
--- a/lib/classes/Seminar.class.php
+++ b/lib/classes/Seminar.class.php
@@ -1611,10 +1611,6 @@ class Seminar
         $statement = DBManager::get()->prepare($query);
         $statement->execute([$s_id]);
 
-        $query = "DELETE FROM wiki_locks WHERE range_id = ?";
-        $statement = DBManager::get()->prepare($query);
-        $statement->execute([$s_id]);
-
         // delete course config values
         ConfigValue::deleteBySQL('range_id = ?', [$s_id]);
 
diff --git a/lib/modules/CoreWiki.class.php b/lib/modules/CoreWiki.class.php
index a52aa4d78e2107c9f9e9e82ec1b00cc2c847e78f..e82fd6582ebd5704579c790da306746c371f49c1 100644
--- a/lib/modules/CoreWiki.class.php
+++ b/lib/modules/CoreWiki.class.php
@@ -183,7 +183,8 @@ class CoreWiki extends CorePlugin implements StudipModule
      */
     public static function getTOC($startPage, $active_title = null): TOCItem
     {
-        $root = new TOCItem($startPage->isNew() || $startPage->name === 'WikiWikiWeb'
+        $root = new TOCItem(
+            ($startPage && ($startPage->isNew() || $startPage->name === 'WikiWikiWeb'))
             ? _('Wiki-Startseite')
             : $startPage->name
         );