尝试上载表单中的文件时出现500内部服务器错误

Question

我正在php中创建一个小应用程序。但是当我试图上传一个单独的fie时，一切正常。它显示我这样的错误。

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete   your request.

Please contact the server administrator at admin@example.com to inform them of the time this error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.

没有img的其他形式可以正常工作。我已经在php.ini＆amp;中找到了post_max_size。升级到20M，但问题仍然存在。

对于测试，我使用简单..

    <?php
    if(isset($_POST['submit']))
    {
        var_dump($_POST);
    }
    ?>

    <form action="" method="post" enctype="multipart/form-data">

    <input type="file" name="img" />
    <input type="submit" name="submit" value="submit" />

    </form>