诊断PHP登录表单问题

我不想找任何人帮我做所有的跑腿工作，但我有一个开源项目，它在大多数服务器上都能完美工作，但在一个人的服务器上，当你注册或登录时，页面只会刷新而不是登录。数据库中没有任何东西。

$_POST的var_dump看起来一切都很好，我在表单中去掉了尽可能多的数据验证，但没有骰子。

Chrome或Firefox/Firebug中有没有工具可以帮助我了解发生了什么？Chrome中的控制台日志基本上只是告诉我页面已经重新加载，但没有其他信息。我的错误都没有再出现在页面上。这只是一个简单的页面刷新。

这是未经编辑的（减去一堆html）登录文件。它基于一个名为UserCake的旧系统。其中大部分是遗留代码。我要从头开始彻底重写这个项目。

<?php require_once("models/top-nav.php"); ?>
<!-- If you are going to include the sidebar, do it here -->
<?php //require_once("models/left-nav.php"); ?>
</div>
<!-- /.navbar-collapse -->
</nav>
<!-- PHP GOES HERE -->
<?php
//Prevent the user visiting the logged in page if he/she is already logged in
if(isUserLoggedIn()) { header("Location: account.php"); die(); }
//Forms posted
if(!empty($_POST))
{
    $token = $_POST['csrf'];
    if(!Token::check($token)){
        die('Token doesn''t match!');
    }
    //reCAPTCHA 2.0 check
    // empty response
    $response = null;
    // check secret key
    $reCaptcha = new ReCaptcha($privatekey);
    // if submitted check response
    if ($_POST["g-recaptcha-response"]) {
        $response = $reCaptcha->verifyResponse(
            $_SERVER["REMOTE_ADDR"],
            $_POST["g-recaptcha-response"]
        );
    }
    if ($response != null && $response->success) {
    $errors = array();
    $username = sanitize2(trim($_POST["username"]));
    $password = trim($_POST["password"]);
    //Perform some validation
    //Feel free to edit / change as required
    if($username == "")
    {
        $errors[] = lang("ACCOUNT_SPECIFY_USERNAME");
    }
    if($password == "")
    {
        $errors[] = lang("ACCOUNT_SPECIFY_PASSWORD");
    }
        //A security note here, never tell the user which credential was incorrect
        if(!usernameExists($username))
        {
        $errors[] = lang("ACCOUNT_USER_OR_PASS_INVALID");
        }
        else
        {
            $userdetails = fetchUserDetails($username);
            //See if the user's account is activated
            if($userdetails["active"]==0)
            {
                $errors[] = lang("ACCOUNT_INACTIVE");
            }
            else
            {
                //- THE OLD SYSTEM IS BEING REMOVED - Hash the password and use the salt from the database to compare the password.
                //$entered_pass = generateHash($password,$userdetails["password"]);
                $entered_pass = password_verify($password,$userdetails["password"]);

                if($entered_pass != $userdetails["password"])
                {
                    $errors[] = lang("ACCOUNT_USER_OR_PASS_INVALID"); //MAKE UPGRADE CHANGE HERE
                }
                else
                {
                    //Passwords match! we're good to go'
                    //Construct a new logged in user object
                    //Transfer some db data to the session object
                    $loggedInUser = new loggedInUser();
                    $loggedInUser->email = $userdetails["email"];
                    $loggedInUser->user_id = $userdetails["id"];
                    $loggedInUser->hash_pw = $userdetails["password"];
                    $loggedInUser->title = $userdetails["title"];
                    $loggedInUser->displayname = $userdetails["display_name"];
                    $loggedInUser->username = $userdetails["user_name"];

                    //Update last sign in
                    $loggedInUser->updateLastSignIn();
                    $_SESSION["userCakeUser"] = $loggedInUser;
                    //Redirect to user account page
                    header("Location: account.php");
                    die();
                }
            }
        }
    }
}
?>

<?php
echo resultBlock($errors,$successes);
echo "
<div id='regbox'>
<form name='login' action='".$_SERVER['PHP_SELF']."' method='post'>
<p>
";
?>
<label>Username:</label>
<input  class='form-control' type='text' name='username' />
</p>
<p>
<label>Password:</label>
<input  class='form-control'  type='password' name='password' />
</p>
<p><label>Please enter the words as they appear:</label>
    <div class="g-recaptcha" data-sitekey="<?php echo $publickey; ?>"></div>
</p>
<p>
<label>&nbsp;</label>
<input class='btn btn-primary' type='submit' value='Login' class='submit' />
</p>
<input type="hidden" name="csrf" value="<?=Token::generate();?>" >
</form>
<script src="https://www.google.com/recaptcha/api.js" async defer></script>
<!-- footer -->
<?php require_once("models/footer.php"); ?>