Ajax请求一直给我500个内部服务器错误

Question

当我在本地服务器上运行它时，我的ajax请求工作正常，但是一旦我将它上传到我的服务器，就没有什么工作了。我的帐户注册页面一直返回：POST http://www.mydomainnottellingyou.net/php/registerUser.php 500（内部服务器错误）

其他文件的链接已正确链接，因为它在本地工作，并且数据库登录用户名和密码也没有任何问题。我已经尝试使用localhost和127.0.0.1让主机连接到数据库。

这是Ajax请求：

var data = {
    username: registerUsername,
    password: loginPassword
};
$.ajax({
    url: "php/registerUser.php",
    data: data,
    method: "POST",
    success: function(response){
        if(response == "1"){
            window.location.replace("roomSelection.php");
        }
        else{
            $("#errorsDiv").html(response);
        }
    }
});

然后是php：

    <?php
    session_start();
    if(isset($_POST["username"]) && isset($_POST["password"])){
        //Validate
        $username = $_POST["username"];
        $password = $_POST["password"];
        if(strlen($username) >= 3 && strlen($username) <= 18 && strlen($password) >=6 && strlen($password) <= 16){
            //Check for special chars
            $allowed = true;
            for($i=0; $i<strlen($username); $i++){
                $charCode = ord($username[$i]);
                if(!(($charCode >= 48 && $charCode <= 57) || ($charCode >= 65 && $charCode <= 90) || ($charCode >= 97 && $charCode <= 122))){
                    $allowed = false;
                }
            }
            if($allowed){
                //Insert user to database now
                include "../lib/databaseHandler.php";
                $dbo = createDBO("chat");
                //Check if username already exists
                $statement = "SELECT * FROM users WHERE username=:username";
                $bindings = [
                    ":username" => $username
                ];
                $query = executeQuery($dbo, $statement, $bindings);
                $numRows = getQueryRowCount($query);
                if($numRows <= 0){
                    //Create user
                    $statement = "INSERT INTO users(username, password) VALUES(:username, :password)";
                    $password = hash("sha256", md5($password));
                    $bindings = [
                        ":username" => $username,
                        ":password" => $password
                    ];
                    $query = executeQuery($dbo, $statement, $bindings);

                    //Get id
                    $statement = "SELECT userId FROM users WHERE username=:username";
                    $bindings = [
                        ":username" => $username
                    ];
                    $query = executeQuery($dbo, $statement, $bindings);
                    $rows = getQueryRows($query);
                    if(isset($rows[0]["userId"])){
                        $_SESSION["chatUserId"] = $rows[0]["userId"];
                    }
                    echo "1";
                }
                else{
                    echo "Username already taken";
                }
            }
        }
    }
?>

还有一个包含文件（databaseHandler.php），如下所示：

 <?php

    function createDBO($dataBase){ //Make Database Object
        if(strtolower($dataBase)=="chat"){
            include $_SERVER['DOCUMENT_ROOT'] . "/PeasFactory/Config/chatDbConfig.php";
        }
        return(new PDO("mysql:host=".$dbConfig["host"].";dbname=".$dbConfig["dbname"],$dbConfig["username"],$dbConfig["password"]));
    }

    function executeQuery($dbo, $statement, $bindings){
        if($dbo != null){
            $query = $dbo->prepare($statement);
            $query->execute($bindings);
        }
        return $query;
    }

    function getQueryRows($query){
        if($query != null){
            return $query->fetchAll();
        }
    }

    function getQueryRowCount($query){
        if($query != null){
            return $query->rowCount();
        }
    }    
?>