diff --git a/typo3/sysext/frontend/Classes/ContentObject/ContentObjectRenderer.php b/typo3/sysext/frontend/Classes/ContentObject/ContentObjectRenderer.php
index 9d54aeccf5..668bf1fdfb 100644
--- a/typo3/sysext/frontend/Classes/ContentObject/ContentObjectRenderer.php
+++ b/typo3/sysext/frontend/Classes/ContentObject/ContentObjectRenderer.php
@@ -3729,11 +3729,11 @@ class ContentObjectRenderer implements LoggerAwareInterface
                         // Removes NL in the beginning and end of the tag-content AND at the end of the currentTagBuffer.
                         // $stripNL depends on the configuration of the current tag
                         if ($stripNL) {
-                            $contentAccum[$contentAccumP - 1] = preg_replace('/' . CR . '?' . LF . '[ ]*$/', '', $contentAccum[$contentAccumP - 1]);
-                            $contentAccum[$contentAccumP] = preg_replace('/^[ ]*' . CR . '?' . LF . '/', '', $contentAccum[$contentAccumP]);
-                            $contentAccum[$contentAccumP] = preg_replace('/' . CR . '?' . LF . '[ ]*$/', '', $contentAccum[$contentAccumP]);
+                            $contentAccum[$contentAccumP - 1] = preg_replace('/' . CR . '?' . LF . '[ ]*$/', '', $contentAccum[$contentAccumP - 1] ?? '');
+                            $contentAccum[$contentAccumP] = preg_replace('/^[ ]*' . CR . '?' . LF . '/', '', $contentAccum[$contentAccumP] ?? '');
+                            $contentAccum[$contentAccumP] = preg_replace('/' . CR . '?' . LF . '[ ]*$/', '', $contentAccum[$contentAccumP] ?? '');
                         }
-                        $this->data[$this->currentValKey] = $contentAccum[$contentAccumP];
+                        $this->data[$this->currentValKey] = $contentAccum[$contentAccumP] ?? '';
                         $newInput = $this->cObjGetSingle($theName, $theConf, '/parseFunc/.tags.' . $tag[0]);
                         // fetch the content object
                         $contentAccum[$contentAccumP] = $newInput;