php - Notice: Undefined index: name

I just installed XAMPP with PHP 7. I had a script that worked before, but after installing there is an error. I will show an example which is also not working. The problem is in $_POST, I think it can be because of configurations in XAMPP or PHP.

echo "
 


";
if (isset($_POST['submit'])){echo $_POST['name'];}
if (isset($_POST['name'])) var_dump($_POST['name']);
?>

This code doesn't return anything, but if I just add echo $_POST['name']; it returns error "Notice: Undefined index: name in D:\XAMPP\php\www\index.php on line 13". How can I fix it?