Change “Read More” button link on Out of stock Woocommerce products

Is it possible to change the Read More button of a out of stock product to redirect to a specific page/url or popup message instead of going to the single product view.

Whenever I have an out of stock product id like to have a popup message appear saying something in a Lightbox window.

Answer

The code below will change the product button link when product is out of stock on Woocommerce archive pages:

add_filter( 'woocommerce_product_add_to_cart_url', 'out_of_stock_read_more_url', 50, 2 );
function out_of_stock_read_more_url( $link, $product  ) {
    // Only for "Out of stock" products
    if( $product->get_stock_status() == 'outofstock' ){

        // Here below we change the link
        $link = home_url("/custom-page/");
    }
    return $link;
}

Code goes in function.php file of your active child theme (or active theme). Tested and works.