diff --git a/src/PhpSpreadsheet/Reader/Csv.php b/src/PhpSpreadsheet/Reader/Csv.php
index 1495d102..92b0f6ac 100644
--- a/src/PhpSpreadsheet/Reader/Csv.php
+++ b/src/PhpSpreadsheet/Reader/Csv.php
@@ -334,7 +334,7 @@ class Csv extends BaseReader
     public function loadIntoExisting($pFilename, Spreadsheet $spreadsheet)
     {
         $lineEnding = ini_get('auto_detect_line_endings');
-        ini_set('auto_detect_line_endings', true);
+        ini_set('auto_detect_line_endings', '1');
 
         // Open file
         $this->openFileOrMemory($pFilename);
@@ -528,7 +528,8 @@ class Csv extends BaseReader
         fclose($this->fileHandle);
 
         // Trust file extension if any
-        $extension = strtolower(pathinfo($pFilename, PATHINFO_EXTENSION));
+        $extension = pathinfo($pFilename, PATHINFO_EXTENSION);
+        $extension = is_array($extension) ? '' : strtolower($extension);
         if (in_array($extension, ['csv', 'tsv'])) {
             return true;
         }
diff --git a/src/PhpSpreadsheet/Reader/Xlsx.php b/src/PhpSpreadsheet/Reader/Xlsx.php
index eafa36b5..c05f77de 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx.php
@@ -186,8 +186,7 @@ class Xlsx extends BaseReader
                 );
                 if ($xmlWorkbook->sheets) {
                     $dir = dirname($rel['Target']);
-                    /** @var SimpleXMLElement $eleSheet */
-                    foreach ($xmlWorkbook->sheets->sheet as $eleSheet) {
+                    foreach ($xmlWorkbook->sheets->sheet->children() as $eleSheet) {
                         $tmpInfo = [
                             'worksheetName' => (string) $eleSheet['name'],
                             'lastColumnLetter' => 'A',
diff --git a/src/PhpSpreadsheet/Reader/Xlsx/Hyperlinks.php b/src/PhpSpreadsheet/Reader/Xlsx/Hyperlinks.php
index 106fd44e..a9afce38 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx/Hyperlinks.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx/Hyperlinks.php
@@ -29,7 +29,9 @@ class Hyperlinks
     public function setHyperlinks(SimpleXMLElement $worksheetXml): void
     {
         foreach ($worksheetXml->hyperlink as $hyperlink) {
-            $this->setHyperlink($hyperlink, $this->worksheet);
+            if ($hyperlink !== null) {
+                $this->setHyperlink($hyperlink, $this->worksheet);
+            }
         }
     }
 
diff --git a/src/PhpSpreadsheet/Spreadsheet.php b/src/PhpSpreadsheet/Spreadsheet.php
index c8e8f72c..51f558a1 100644
--- a/src/PhpSpreadsheet/Spreadsheet.php
+++ b/src/PhpSpreadsheet/Spreadsheet.php
@@ -373,7 +373,9 @@ class Spreadsheet
      */
     private function getExtensionOnly($path)
     {
-        return pathinfo($path, PATHINFO_EXTENSION);
+        $extension = pathinfo($path, PATHINFO_EXTENSION);
+
+        return is_array($extension) ? '' : $extension;
     }
 
     /**