diff --git a/typo3/sysext/backend/Classes/Controller/PageLayoutController.php b/typo3/sysext/backend/Classes/Controller/PageLayoutController.php
index 60b3f7c3ead06be670caee5a4e31e7d9f8452dcb..5cff6102b605ba8bf12e68364d1269afe3c8df84 100644
--- a/typo3/sysext/backend/Classes/Controller/PageLayoutController.php
+++ b/typo3/sysext/backend/Classes/Controller/PageLayoutController.php
@@ -703,8 +703,8 @@ class PageLayoutController
         }
 
         $this->pageRenderer->addInlineLanguageLabelFile('EXT:backend/Resources/Private/Language/locallang_layout.xlf');
+        $h_func_b = '';
         if ($this->getBackendUser()->check('tables_select', 'tt_content')) {
-            $h_func_b = '';
             // Toggle hidden ContentElements
 
             if ($numberOfHiddenElements > 0) {
diff --git a/typo3/sysext/backend/Classes/Form/FormDataProvider/TcaFlexPrepare.php b/typo3/sysext/backend/Classes/Form/FormDataProvider/TcaFlexPrepare.php
index fa0a5d4ad4af3b5e9a742957bfbe3def0c1bf8a2..42c46ef0e1b81019f33c8eb65687108302ae46cf 100644
--- a/typo3/sysext/backend/Classes/Form/FormDataProvider/TcaFlexPrepare.php
+++ b/typo3/sysext/backend/Classes/Form/FormDataProvider/TcaFlexPrepare.php
@@ -83,6 +83,7 @@ class TcaFlexPrepare implements FormDataProviderInterface
                 );
                 $dataStructureArray = $flexFormTools->parseDataStructureByIdentifier($dataStructureIdentifier);
             } catch (InvalidParentRowException|InvalidParentRowLoopException|InvalidParentRowRootException|InvalidPointerFieldValueException|InvalidIdentifierException $e) {
+                $dataStructureIdentifier = null;
             } finally {
                 // Add the identifier to TCA to use it later during rendering
                 $result['processedTca']['columns'][$fieldName]['config']['dataStructureIdentifier'] = $dataStructureIdentifier;
diff --git a/typo3/sysext/backend/Classes/View/PageLayoutView.php b/typo3/sysext/backend/Classes/View/PageLayoutView.php
index bc87af86bebc501ec87bf29e0164bb80441c208b..5e8c13a9c3b97e14ddfa0fbea556b3432f5cf54b 100644
--- a/typo3/sysext/backend/Classes/View/PageLayoutView.php
+++ b/typo3/sysext/backend/Classes/View/PageLayoutView.php
@@ -521,6 +521,8 @@ class PageLayoutView implements LoggerAwareInterface
                 // Add colgroups
                 $colCount = (int)$backendLayout['__config']['backend_layout.']['colCount'];
                 $rowCount = (int)$backendLayout['__config']['backend_layout.']['rowCount'];
+                $colSpan = 0;
+                $rowSpan = 0;
                 $grid .= '<colgroup>';
                 for ($i = 0; $i < $colCount; $i++) {
                     $grid .= '<col />';
diff --git a/typo3/sysext/core/Classes/Authentication/BackendUserAuthentication.php b/typo3/sysext/core/Classes/Authentication/BackendUserAuthentication.php
index 9cb8a2b9d27c7c8a0b249009be46ef219a0cf31d..0c63d25e503e8ae9db212ba793a158c597621a4f 100644
--- a/typo3/sysext/core/Classes/Authentication/BackendUserAuthentication.php
+++ b/typo3/sysext/core/Classes/Authentication/BackendUserAuthentication.php
@@ -375,6 +375,7 @@ class BackendUserAuthentication extends AbstractUserAuthentication
         if (!$GLOBALS['TYPO3_CONF_VARS']['BE']['lockBeUserToDBmounts'] || $this->isAdmin()) {
             return 1;
         }
+        $checkRec = [];
         $fetchPageFromDatabase = true;
         if (is_array($idOrRow)) {
             if (empty($idOrRow['uid'])) {
diff --git a/typo3/sysext/core/Classes/DataHandling/DataHandler.php b/typo3/sysext/core/Classes/DataHandling/DataHandler.php
index ca79781e3903dd5b051589b6b5c5f203f5c7ac83..47bcd1b85216b405f982767c390682aa07b32d6d 100644
--- a/typo3/sysext/core/Classes/DataHandling/DataHandler.php
+++ b/typo3/sysext/core/Classes/DataHandling/DataHandler.php
@@ -5655,6 +5655,7 @@ class DataHandler implements LoggerAwareInterface
             $remapFlexForms = [];
             $hookPayload = [];
 
+            $newValue = null;
             foreach ($this->remapStack as $remapAction) {
                 // If no position index for the arguments was set, skip this remap action:
                 if (!is_array($remapAction['pos'])) {
diff --git a/typo3/sysext/indexed_search/Classes/Hook/CrawlerHook.php b/typo3/sysext/indexed_search/Classes/Hook/CrawlerHook.php
index 3c377b1fdc73733aae3e8670dc1143eb318e3c63..7faf6cdfa080adf3d246ac9a0a0b293e1781c450 100644
--- a/typo3/sysext/indexed_search/Classes/Hook/CrawlerHook.php
+++ b/typo3/sysext/indexed_search/Classes/Hook/CrawlerHook.php
@@ -668,6 +668,7 @@ class CrawlerHook
         $indexerObj->backend_setFreeIndexUid($cfgRec['uid'], $cfgRec['set_id']);
         $indexerObj->forceIndexing = true;
         $theContent = '';
+        $theTitle = '';
         foreach ($fieldList as $k => $v) {
             if (!$k) {
                 $theTitle = $r[$v];
diff --git a/typo3/sysext/indexed_search/Classes/Indexer.php b/typo3/sysext/indexed_search/Classes/Indexer.php
index c5bd05535cf7136965aa6a54efcb4cad55f26167..74c42863fb0a5329748e50651bec887d3ca0d0be 100644
--- a/typo3/sysext/indexed_search/Classes/Indexer.php
+++ b/typo3/sysext/indexed_search/Classes/Indexer.php
@@ -706,6 +706,7 @@ class Indexer
         $expBody = preg_split('/\\<\\!\\-\\-[\\s]?TYPO3SEARCH_/', $body);
         if (count($expBody) > 1) {
             $body = '';
+            $prev = '';
             foreach ($expBody as $val) {
                 $part = explode('-->', $val, 2);
                 if (trim($part[0]) === 'begin') {