nopCommerce version

4.90 (plugin Payments.PayPalCommerce v4.90.20). Reproduced on our production store running a backport of the same plugin; the affected code in 4.90.20 is identical.

Steps to reproduce

1. Configure the PayPal Commerce plugin with buttons displayed on the shopping cart page (DisplayButtonsOnShoppingCart = true).
2. Make sure ShippingSettings.AllowPickupInStore is disabled.
3. As a guest (or any customer without a saved shipping address), add a shippable product to the cart.
4. On the cart page, click the PayPal button.

Actual result: the AJAX call to PayPalCommercePublic/CreateOrder returns the error "No available shipping options" and the PayPal popup closes/never opens. Guests can never use the express buttons — which is their primary use case, since the address is supposed to be collected by PayPal.

Expected result: the PayPal order is created, the buyer picks/confirms their address in the PayPal popup (the plugin already sends shipping_preference = GET_FROM_FILE for the Cart/Product placements), and the shipping options are computed by the existing onShippingAddressChange → UpdateOrderShipping callback.

Root cause

PayPalCommerceServiceManager.PrepareShippingDetailsAsync:

• For the Cart/Product placement it calls PrepareShippingOptionsAsync(details).
• PrepareShippingOptionsAsync returns an empty result when details.ShippingAddress is null && !_shippingSettings.AllowPickupInStore — which is always the case for a guest, because details.ShippingAddress comes from customer.ShippingAddressId in GetCartDetailsAsync.
• PrepareShippingDetailsAsync then throws new NopException("No available shipping options"), which aborts CreateOrder.

So the order creation requires a shipping address that, by design of the express flow (GET_FROM_FILE), doesn't exist yet.

Notes

• Registered customers with a saved shipping address are unaffected, which is probably why this slipped through.
• The buttons on the checkout payment-method page are unaffected (SET_PROVIDED_ADDRESS branch returns before the options are computed).
• Stores with AllowPickupInStore enabled are partially masked from the bug because pickup points populate the options list.