mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given in

Answer 1

use AND insted of comma (,) in query near password that's why query returning false and throw that error

$select = "SELECT id FROM loginregistration WHERE login ='".$login1."' and password ='".$password1."'";

UPDATE 1

if query fail it return false . so you can use mysqli_error($con); to know the error

    <?php
    require_once("connect.php");

    $login1 = $_POST['email'];
    $password1 = $_POST['password'];
    $select = "SELECT id FROM loginregistration WHERE login ='".$login1."' AND password   ='".$password1."'";
    $sql = mysqli_query($con,$select);

    if($sql === FALSE) { 
        die(mysqli_error($con)); // better error handling
    }

    $row = mysqli_fetch_assoc($sql);
    ?>