diff --git a/typo3/sysext/impexp/Classes/Controller/ExportController.php b/typo3/sysext/impexp/Classes/Controller/ExportController.php
index b6471c77d9fbe8a4080d5222d251db68904f119c..599ca146f525b1d29d0713487405e1f6bb981a10 100644
--- a/typo3/sysext/impexp/Classes/Controller/ExportController.php
+++ b/typo3/sysext/impexp/Classes/Controller/ExportController.php
@@ -217,24 +217,24 @@ class ExportController
         if (!empty($inputData['filetype'])) {
             $export->setExportFileType((string)$inputData['filetype']);
         }
-        $export->setExportFileName($inputData['filename'] ?? '');
-        $export->setRelStaticTables($inputData['external_static']['tables']);
-        $export->setRelOnlyTables($inputData['external_ref']['tables']);
+        $export->setExportFileName((string)($inputData['filename'] ?? ''));
+        $export->setRelStaticTables((($inputData['external_static']['tables'] ?? '') === '') ? [] : (array)$inputData['external_static']['tables']);
+        $export->setRelOnlyTables((($inputData['external_ref']['tables'] ?? '') === '') ? [] : (array)$inputData['external_ref']['tables']);
         if (isset($inputData['save_export'], $inputData['saveFilesOutsideExportFile']) && $inputData['saveFilesOutsideExportFile'] === '1') {
             $export->setSaveFilesOutsideExportFile(true);
         }
-        $export->setTitle($inputData['meta']['title']);
-        $export->setDescription($inputData['meta']['description']);
-        $export->setNotes($inputData['meta']['notes']);
-        $export->setRecord($inputData['record']);
-        $export->setList($inputData['list']);
+        $export->setTitle((string)($inputData['meta']['title'] ?? ''));
+        $export->setDescription((string)($inputData['meta']['description'] ?? ''));
+        $export->setNotes((string)($inputData['meta']['notes'] ?? ''));
+        $export->setRecord((($inputData['record'] ?? '') === '') ? [] : (array)$inputData['record']);
+        $export->setList((($inputData['list'] ?? '') === '') ? [] : (array)$inputData['list']);
         if (MathUtility::canBeInterpretedAsInteger($inputData['pagetree']['id'] ?? null)) {
             $export->setPid((int)$inputData['pagetree']['id']);
         }
         if (MathUtility::canBeInterpretedAsInteger($inputData['pagetree']['levels'] ?? null)) {
             $export->setLevels((int)$inputData['pagetree']['levels']);
         }
-        $export->setTables($inputData['pagetree']['tables']);
+        $export->setTables((($inputData['pagetree']['tables'] ?? '') === '') ? [] : (array)$inputData['pagetree']['tables']);
         return $export;
     }
 
diff --git a/typo3/sysext/impexp/Classes/Import.php b/typo3/sysext/impexp/Classes/Import.php
index 1984b02ac3a2a1419131dd113bff78524a693c43..3d4716ac3c3ce3cabb39a36338f4796982f4eebc 100644
--- a/typo3/sysext/impexp/Classes/Import.php
+++ b/typo3/sysext/impexp/Classes/Import.php
@@ -1046,7 +1046,9 @@ class Import extends ImportExport
                         // @see fixUidLocalInSysFileReferenceRecords()
                         // If it's empty or a uid to another record the FileExtensionFilter will throw an exception or
                         // delete the reference record if the file extension of the related record doesn't match.
-                        if (!($table === 'sys_file_reference' && $field === 'uid_local')) {
+                        if (!($table === 'sys_file_reference' && $field === 'uid_local')
+                            && is_array($GLOBALS['TCA'][$table]['columns'][$field]['config'] ?? false)
+                        ) {
                             $importData[$table][$ID][$field] = $this->getReferenceDefaultValue($GLOBALS['TCA'][$table]['columns'][$field]['config']);
                         }
                         break;
@@ -1449,7 +1451,7 @@ class Import extends ImportExport
                 if (isset($GLOBALS['TCA'][$table])) {
                     foreach ($records as $uid => $record) {
                         if (is_array($record['softrefs'] ?? null)) {
-                            $actualUid = BackendUtility::wsMapId($table, $this->importMapId[$table][$uid]);
+                            $actualUid = BackendUtility::wsMapId($table, $this->importMapId[$table][$uid] ?? 0);
                             // First, group soft references by record field ...
                             // (this could probably also have been done with $this->dat['records'] instead of $this->dat['header'])
                             $softrefs = [];