If you are using any other plugin along with WP Crowdfunding and that requires shipping, then there might be a conflict with the shipping gateway. To avoid that, you can disable the shipping system for WP Crowdfunding products.
You need to add the following snippet in the wp-crowdfunding/includes/woocommerce/Woocommerce.php file. The line number is 55.
add_filter( 'woocommerce_cart_needs_shipping_address', array($this, 'disable_shipping') );
add_filter( 'woocommerce_cart_ready_to_calc_shipping', array($this, 'disable_shipping'), 99);
function disable_shipping() {
global $woocommerce;
$has_crowdfunding_product = false;
$items = $woocommerce->cart->get_cart();
if( $items) {
foreach($items as $item => $values) {
$product = wc_get_product( $values['product_id'] );
if( $product->get_type() == 'crowdfunding' ){
$has_crowdfunding_product = true;
}
}
}
return !$has_crowdfunding_product;
}