Woocommerce redirect after add-to-cart error

php wordpress woocommerce

PHP Snippet 1:

 function firefog_custom_add_to_cart_redirect( $url ) {
        $url = WC()->cart->get_cart_url();
        return $url;
    }
    add_filter( 'woocommerce_cart_redirect_after_error', 'firefog_custom_add_to_cart_redirect' );

PHP Snippet 2:

function firefog_custom_add_to_cart_redirect( $url ) {
    $url = WC()->cart->get_checkout_url();
    return $url;
}
add_filter( 'woocommerce_add_to_cart_redirect', 'firefog_custom_add_to_cart_redirect' );

PHP Snippet 3:

   <?php
    $url = $_SERVER['REQUEST_URI'];
      //change "ID" to your product id number (example:/shop/?add-to-cart=22 )
    if($url==="/shop/?add-to-cart=ID"){
    //change "/checkout" if your checkout page has a different url.
    header("Location: /checkout");
    die();
    } else {
     //your normal 404 page code here...
    } ?>