我正在使用InfinityFree托管我的mysql数据库，并希望将数据从我的React Native按钮按下到服务器端API但这个“AXIOS错误[AxiosError：请求失败，状态代码为400]”错误。请帮帮我

//.js

const insertData = async () => {  
    const firstName = 'John';
    const lastName = 'Doe'; 
  
    try {

      var postData = JSON.stringify({
        firstName,
        lastName,
      });
      
      let axiosConfig = {
        headers: {
          'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8',
            "Access-Control-Allow-Origin": "*",
            "Accept": "application/json" 
        }
      };

      axios.post('http://mywebsite.great-site.net/insert.php', postData, axiosConfig)
      .then((res) => {
        console.log("RESPONSE RECEIVED: ", res);
      })
      .catch((err) => {
        console.log("AXIOS ERROR: ", err);
      })
 
    } catch (error) {
      console.error('Error inserting data:', error);
    }
  };

字符串
此外，我已经注意到，错误只显示了每隔一个按钮按下。

//insert.php in infinityfree domain file manager

<?php 
    $host = "sql213.infinityfree.com";
    $username = "if0_00000000";
    $password = "password";
    $database = "if0_34528777_mydatabase";
 
    $conn = new mysqli($host, $username, $password, $database);

    // Check the connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    } 

    // Check if the request is a POST request
    if ($_SERVER["REQUEST_METHOD"] === "POST") {
        // Get the data from the POST request (sent from React Native app) 
        $Acc_FirstName = $_POST["firstName"];
        $Acc_LastName = $_POST["lastName"]; 

        // Prepare the SQL query to insert the data into the database
        $sql = "INSERT INTO `user`(`Acc_FirstName`, `Acc_LastName`) VALUES (?, ?)";
        $stmt = $conn->prepare($sql);
        $stmt->bind_param("ss", $Acc_FirstName, $Acc_LastName);

        // Execute the query and check for success
        if ($stmt->execute()) {
            // Data inserted successfully
            $response["success"] = true;
            $response["message"] = "Data inserted successfully";
        } else {
            // Failed to insert data
            $response["success"] = false;
            $response["message"] = "Failed to insert data: " . $conn->error;
        }

        // Close the prepared statement
        $stmt->close();
    } else {
        // Invalid request method
        $response["success"] = false;
        $response["message3"] = "Invalid request method";
    }

    // Set the response headers to indicate JSON content type
    header(
        // "Content-Type: application/json"
        {
          'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8',
            "Access-Control-Allow-Origin": "*",
            "Accept": "application/json"
        });

    // Send the JSON response back to the React Native app
    echo json_encode($response);

    // Close the database connection
    $conn->close();
?>

型
这是我第一次这样做，所以我从其他帖子中学习，并向chatgpt寻求帮助