解析数据时格式错误的JSON响应

Question

Using Postman to see if this section of php works as intended, however Postman returns the error Malformed JSON: Unexpected 'U' and the database is not updated, can't get my head around this error as it looks fine to me?

Code:

function placeVoteForCandidate()
{
    global $connect;

    $username = $_POST["username"];

    $query = "UPDATE User SET votesAttained=votesAttained+1 WHERE USER_NAME = $username";

    mysqli_query($connect, $query) or die (mysqli_error($connect));
    mysqli_close($connect);

    $message['success'] = 'Vote added';
    echo json_encode($message);
}

Answer 1

When executing just

echo json_encode('Vote added');

there should be no problem. Is there any exception thrown causing this error? Try to change the SQL statement to

$query = "UPDATE User SET votesAttained=votesAttained+1 WHERE USER_NAME = " . $username;