--- web/typo3/sysext/extbase/Classes/Persistence/Generic/Mapper/DataMapper.php	2024-10-03 11:04:47.000000000 +0200
+++ web/typo3/sysext/extbase/Classes/Persistence/Generic/Mapper/DataMapper.php	2024-10-03 11:16:25.000000000 +0200
@@ -25,6 +25,7 @@
 use TYPO3\CMS\Extbase\Object\Exception\CannotReconstituteObjectException;
 use TYPO3\CMS\Extbase\Object\ObjectManagerInterface;
 use TYPO3\CMS\Extbase\Persistence;
+use TYPO3\CMS\Extbase\Persistence\ClassesConfiguration;
 use TYPO3\CMS\Extbase\Persistence\Generic\Exception;
 use TYPO3\CMS\Extbase\Persistence\Generic\Exception\UnexpectedTypeException;
 use TYPO3\CMS\Extbase\Persistence\Generic\LazyLoadingProxy;
@@ -57,6 +58,10 @@
     // @deprecated since v11, will be removed in v12
     protected ObjectManagerInterface $objectManager;
     protected EventDispatcherInterface $eventDispatcher;
+    /**
+     * @var ClassesConfiguration
+     */
+    private $classesConfiguration;
 
     /**
      * @var QueryInterface|null
@@ -70,7 +75,8 @@
         DataMapFactory $dataMapFactory,
         QueryFactoryInterface $queryFactory,
         ObjectManagerInterface $objectManager,
-        EventDispatcherInterface $eventDispatcher
+        EventDispatcherInterface $eventDispatcher,
+        ClassesConfiguration $classesConfiguration,
     ) {
         $this->reflectionService = $reflectionService;
         $this->qomFactory = $qomFactory;
@@ -80,6 +86,7 @@
         // @deprecated since v11, will be removed in v12.
         $this->objectManager = $objectManager;
         $this->eventDispatcher = $eventDispatcher;
+        $this->classesConfiguration = $classesConfiguration;
     }
 
     /**
@@ -138,11 +145,17 @@
      */
     protected function mapSingleRow($className, array $row)
     {
-        if ($this->persistenceSession->hasIdentifier($row['uid'], $className)) {
-            $object = $this->persistenceSession->getObjectByIdentifier($row['uid'], $className);
+        $classSettings = $this->classesConfiguration->getConfigurationFor($className);
+        $uidColumnName = 'uid';
+        if ($classSettings && array_key_exists($uidColumnName, $classSettings['properties'])) {
+            $uidColumnName = $classSettings['properties'][$uidColumnName]['fieldName'];
+        }
+
+        if ($this->persistenceSession->hasIdentifier($row[$uidColumnName], $className)) {
+            $object = $this->persistenceSession->getObjectByIdentifier($row[$uidColumnName], $className);
         } else {
             $object = $this->createEmptyObject($className);
-            $this->persistenceSession->registerObject($object, $row['uid']);
+            $this->persistenceSession->registerObject($object, $row[$uidColumnName]);
             $this->thawProperties($object, $row);
             $event = new AfterObjectThawedEvent($object, $row);
             $this->eventDispatcher->dispatch($event);