Uncaught Argument Error With MySQL Prepared Update Statement [duplicate]

I am working on a News article update page and I am experiencing a problem that generates the following error when the update form is submitted. I am using PHP with MySQL.

Uncaught ArgumentCountError: The number of elements in the type definition string must match the number of bind variables

Here is the code snippet containing the query with the PreparedStatement.

if (isset($_POST['submit']))
{
    $aid = $_GET['id'];
    $atitle = $_POST['title'];
    $aauthor = $_POST['author'];
    $acat = $_POST['category'];
    $acontent = $_POST['content'];
    $apublishdate = $_POST['publishdate'];

    $stmt = mysqli_prepare($conn, "UPDATE news_articles SET article_category = ?, article_publish_date = ?, article_title = ?, article_author = ?, article_content = ? WHERE article_id = ?");
    $stmt->bind_param($acat, $apublishdate, $atitle, $aauthor, $acontent, $aid);
    $stmt->execute();
}

Please let me know if you need any additional code. I appreciate any suggestions. Thanks in advance!

source https://stackoverflow.com/questions/77129537/uncaught-argument-error-with-mysql-prepared-update-statement