更改密码PHP问题

Question

I am running the following code below to try and update my current password in my database to the new one being specified in the form that is being to allow for password changes. I am entering the same passwords in both fields so I don't understand why the error is occuring.

      <form method='post' action="changepasswordphp.php">

        <p align="center"><strong> Complete the form to change your password </strong> </p>
            <br/>
                <label><strong>Enter Old Password:</strong></label>                 
                <input name='oldpw' type='password' required='required'/>
            <br/>
            <br/>
                <label><strong>Enter New Password:</strong></label>
                <input name='newpw' type='password' required = 'required' />  
            <br/>
            <br/>
                <label><strong>Confirm New Password:</strong></label>               
                <input name='conpw' type='password' required = 'required' />
            <br/>
            <br/>
                <input type='submit' value='Submit' class ="submit" id="submit" />          
        </form>

$mysqli = new mysqli("localhost", "root", "DBPASS", "DBNAME");
if (isset($_POST['newpw'])){
$pw=$mysqli->query("SELECT userPass FROM usertable WHERE userID= '" . $_SESSION['sess_uid'] . "'");
            $row = $pw->fetch_object();
            $pawo = $row->userPass; 

if (md5($_POST['oldpw'])== $pawo){

    if (md5($_POST['newpw'])===(md5($_POST['conpw']))){
     $mysqli->query("UPDATE usertable SET userPass='" . md5($_POST['newpw']) . "' WHERE userID='" . $_SESSION['sess_uid'] . "'");
     }
    else { echo "Passwords don't match"; }
    }

else { echo "An Error Occured";}
}

?>
I am getting the error message "An Error Occured", I am unsure as to what is causing this problem. Any help would be greatly appreciated!

Thanks

Answer 1

I'm not explicitly familiar with the MySQLi code, but this looks wrong:

$pw=@$mysqli->query("SELECT userPass FROM usertable WHERE userID= '" . $_SESSION['sess_uid'] . "'");
        $row = $pw->fetch_object();
        $pawo = $row->password ; 

Is the password field userPass or password ? Also, don't use MD5 (use password_hash ) and don't use == for comparing hashed passwords. (use === instead)