php – wc_add_notice not engaged on cart web page

Does anybody know find out how to cease the transition to the checkout web page after one clicks “proceed to checkout” on the cart web page? I carried out a validation on the checkout web page that labored completely with wc_add_notice(“Some message right here”). Nevertheless, when I attempt to do the identical proccess on the cart web page, I’m taken to the checkout web page with the error message. I even tried redirecting customers with the header(), however nonetheless get taken to the checkout web page regardless.

Right here is my code:

add_action('woocommerce_proceed_to_checkout', 'username_check');

perform username_check() {


    
     if ( ! $_POST['username_value'] ) {
        wc_add_notice( __( 'Enter your appropriate username' ), 'error' );

        }

     if ( ! $_POST['password_value'] ) {
        wc_add_notice( __( 'Enter your appropriate password' ), 'error' );

        }
    
}