Undefined index: $fileName = basename($_FILES["file"]["name"]);file in D:\xampp\htdocs\upload.php on line 12 code example

Example: Undefined index: $fileName = basename($_FILES["file"]["name"]);file in D:\xampp\htdocs\upload.php on line 12

Undefined index: file in D:\xampp\htdocs\codexworld\upload.php on line 8