diff --git a/Classes/Backend/Shortcut/ShortcutRepository.php b/Classes/Backend/Shortcut/ShortcutRepository.php
index 4bc590799..ff8e6cc29 100644
--- a/Classes/Backend/Shortcut/ShortcutRepository.php
+++ b/Classes/Backend/Shortcut/ShortcutRepository.php
@@ -134,7 +134,7 @@ public function getGroupsFromShortcuts(): array
         $groups = [];
 
         foreach ($this->shortcuts as $shortcut) {
-            $groups[$shortcut['group']] = $this->shortcutGroups[$shortcut['group']];
+            $groups[$shortcut['group']] = $this->shortcutGroups[$shortcut['group']] ?? '';
         }
 
         return array_unique($groups);
diff --git a/Classes/Search/LiveSearch/LiveSearch.php b/Classes/Search/LiveSearch/LiveSearch.php
index 6e27ed5d4..79ffe1235 100644
--- a/Classes/Search/LiveSearch/LiveSearch.php
+++ b/Classes/Search/LiveSearch/LiveSearch.php
@@ -183,7 +183,7 @@ protected function findByTable($tableName, $pageIdList, $firstResult, $maxResult
                 $queryBuilder->andWhere($this->userPermissions);
             }
 
-            $orderBy = $GLOBALS['TCA'][$tableName]['ctrl']['sortby'] ?? $GLOBALS['TCA'][$tableName]['ctrl']['default_sortby'];
+            $orderBy = $GLOBALS['TCA'][$tableName]['ctrl']['sortby'] ?? $GLOBALS['TCA'][$tableName]['ctrl']['default_sortby'] ?? '';
             foreach (QueryHelper::parseOrderBy((string)$orderBy) as $orderPair) {
                 [$fieldName, $order] = $orderPair;
                 $queryBuilder->addOrderBy($fieldName, $order);
diff --git a/Classes/Utility/BackendUtility.php b/Classes/Utility/BackendUtility.php
index f18536123..1a80e8ecd 100644
--- a/Classes/Utility/BackendUtility.php
+++ b/Classes/Utility/BackendUtility.php
@@ -655,7 +655,7 @@ public static function getTCAtypeValue($table, $row)
                         );
                     }
                     $foreignRow = self::getRecord($foreignTable, $foreignUid, $foreignTableTypeField);
-                    if ($foreignRow[$foreignTableTypeField]) {
+                    if ($foreignRow[$foreignTableTypeField] ?? false) {
                         $typeNum = $foreignRow[$foreignTableTypeField];
                     }
                 }
@@ -2750,7 +2750,7 @@ public static function getModuleData(
                                 $changed = 1;
                             }
                         } else {
-                            if ((string)$settings[$key] !== (string)$CHANGED_SETTINGS[$key]) {
+                            if ((string)($settings[$key] ?? '') !== (string)($CHANGED_SETTINGS[$key] ?? '')) {
                                 $settings[$key] = $CHANGED_SETTINGS[$key];
                                 $changed = 1;
                             }