Admin Panel 404 Error after login

I should have changed false to true in the line $login = wp_signon( $creds, false );

so the final working code is

if($_POST){
    if (!empty($_POST['username']) && !empty($_POST['password'])) {
        $creds = array(
            'user_login'    => $_POST['username'],
            'user_password' => $_POST['password'],
            'remember'      => true
            );
        $login = wp_signon( $creds, true);
        if ( is_wp_error( $login ) ) {
            $exiturl = get_site_url().'/account/auth';
            header("Location: $exiturl");
            exit();
        }
} else {
    echo "access denied";
}