diff --git a/typo3/sysext/beuser/Classes/Service/UserInformationService.php b/typo3/sysext/beuser/Classes/Service/UserInformationService.php
index fc06aff9bcab0a7a0e63d7ee77cc79df1245baba..ffb96902bde485515da69cbdef2242d91d6606e1 100644
--- a/typo3/sysext/beuser/Classes/Service/UserInformationService.php
+++ b/typo3/sysext/beuser/Classes/Service/UserInformationService.php
@@ -63,6 +63,10 @@ class UserInformationService
             'uid' => PHP_INT_MAX,
             'options' => 3,
             'workspace_id' => -99,
+            'realName' => 'fakeUser',
+            'email' => 'fake.user@typo3.org',
+            'TSconfig' => '',
+            'category_perms' => '',
             $user->usergroup_column => $groupId,
         ];
         $user->fetchGroupData();
@@ -169,7 +173,7 @@ class UserInformationService
         // Modules
         $modules = GeneralUtility::trimExplode(',', $user->groupData['modules'], true);
         foreach ($modules as $module) {
-            $data['modules'][$module] = $GLOBALS['TBE_MODULES']['_configuration'][$module];
+            $data['modules'][$module] = $GLOBALS['TBE_MODULES']['_configuration'][$module] ?? '';
         }
         $data['modules'] = array_filter($data['modules']);
 
diff --git a/typo3/sysext/core/Classes/Authentication/BackendUserAuthentication.php b/typo3/sysext/core/Classes/Authentication/BackendUserAuthentication.php
index 2bbebf260c1a98574a98166e469f53a185a0845a..664e63c4feff44c32345e8e2fa5db282dafdc601 100644
--- a/typo3/sysext/core/Classes/Authentication/BackendUserAuthentication.php
+++ b/typo3/sysext/core/Classes/Authentication/BackendUserAuthentication.php
@@ -270,7 +270,7 @@ class BackendUserAuthentication extends AbstractUserAuthentication
      */
     public function isAdmin()
     {
-        return is_array($this->user) && ($this->user['admin'] & 1) == 1;
+        return is_array($this->user) && (($this->user['admin'] ?? 0) & 1) == 1;
     }
 
     /**
@@ -1121,7 +1121,7 @@ class BackendUserAuthentication extends AbstractUserAuthentication
         if ($this->user['uid']) {
             // Get lists for the be_user record and set them as default/primary values.
             // Enabled Backend Modules
-            $this->groupData['modules'] = $this->user['userMods'];
+            $this->groupData['modules'] = $this->user['userMods'] ?? '';
             // Add available widgets
             $this->groupData['available_widgets'] = $this->user['available_widgets'] ?? '';
             // Add allowed mfa providers
@@ -1129,13 +1129,13 @@ class BackendUserAuthentication extends AbstractUserAuthentication
             // Add Allowed Languages
             $this->groupData['allowed_languages'] = $this->user['allowed_languages'] ?? '';
             // Set user value for workspace permissions.
-            $this->groupData['workspace_perms'] = $this->user['workspace_perms'];
+            $this->groupData['workspace_perms'] = $this->user['workspace_perms'] ?? 0;
             // Database mountpoints
-            $this->groupData['webmounts'] = $this->user['db_mountpoints'];
+            $this->groupData['webmounts'] = $this->user['db_mountpoints'] ?? '';
             // File mountpoints
-            $this->groupData['filemounts'] = $this->user['file_mountpoints'];
+            $this->groupData['filemounts'] = $this->user['file_mountpoints'] ?? '';
             // Fileoperation permissions
-            $this->groupData['file_permissions'] = $this->user['file_permissions'];
+            $this->groupData['file_permissions'] = $this->user['file_permissions'] ?? '';
 
             // Get the groups and accumulate their permission settings
             $mountOptions = new BackendGroupMountOption($this->user['options']);