Here's the mod from X-cart tech support:
Code:
Please open cart.php and replace in the file
} elseif($mode=="checkout" && empty($paymentid) && !func_is_cart_empty($cart) && $cart["total_cost"] == 0) {
x_session_unregister('paypal_begin_express');
func_header_location($current_location."/payment/payment_offline.php");
with
#} elseif($mode=="checkout" && empty($paymentid) && !func_is_cart_empty($cart) && $cart["total_cost"] == 0) {
# x_session_unregister('paypal_begin_express');
# func_header_location($current_location."/payment/payment_offline.php");
The code is slightly different in 4.0.13, so just look for the elseif with ["total_cost"] == 0 and comment out that statement.
-Glen