Php 此脚本中的PDO错误|页面变为空白

我在这个脚本中使用PDO时遇到了一个奇怪的问题。可能问题很简单，但我找不到，这让我发疯。 问题是当我启动脚本时，页面将变为空白

<?php

    //PDO
if(isset($_POST['submit'])) {   
    // test row

    $password = $_POST['upassword'];
    $email = $_POST['email'];
    $_SESSION['email'] = $email;

    $servername = "localhost";
    $username = "root";
    $password = "passwordxyz";
    $dbname = "abcd";

    try {
        $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

        $statement = $conn->prepare('SELECT `password` FROM `users` WHERE `email` = :email');  
        $statement->bindParam(':email', $email);  
        $statement->execute();  
        while($row = $statement->fetch() ){  
            echo 'ok';  
        }       
    }
} 


?>

请帮我解决这个问题。

---

谢谢。

您有

try

子句，但没有

catch

，这就是产生错误的原因

<?php

//PDO
if(isset($_POST['submit'])) {   

$password = $_POST['upassword'];
$email = $_POST['email'];
$_SESSION['email'] = $email;
$servername = "localhost";
$username = "root";
$password = "passwordxyz";
$dbname = "abcd";

try{
      $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
      // set the PDO error mode to exception
      $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
      $statement = $conn->prepare('SELECT `password` FROM `users` WHERE `email` = :email');  
      $statement->bindParam(':email', $email);  
      $statement->execute();  
      while($row = $statement->fetch() ){  
          echo 'ok';  
      }
   }
catch(Exception $e){
        //change from general to specific exception and handle here
    }
}

---

一个“500内部服务器错误”状态代码（或一个空白页）表示您的脚本正在抛出一个错误，但您尚未将PHP配置为显示错误消息。这是你在继续之前需要解决的问题；如果没有错误消息的帮助，就不可能正确地编写代码。这是一个例子。错误报告的经验法则是：在开发中显示，在生产中登录。感谢您的回答，我打开了错误消息，它说：致命错误：不能使用try with catch或finally in/var/www/core/login.php，第41行