docs: add a troubleshooting section on creating a payment session with zero total (#12974)

www/apps/resources/app/storefront-development/checkout/payment/page.mdx

@@ -278,6 +278,23 @@ In the `Fetch API` example, the `handlePayment` function implements this flow by
 
 ---
 
+## Troubleshooting
+
+### Unknown Error for Zero Cart Total
+
+If your cart has a total of `0`, you might encounter an `unknown error` when trying to create a payment session.
+
+Some payment providers, such as Stripe, require a non-zero amount to create a payment session. So, if your cart has a total of `0`, the error will be thrown on the payment provider's side.
+
+In those cases, you can either:
+
+- Make sure the payment session is only initialized when the cart has a total greater than `0`.
+- Use payment providers like the Manual System Payment Provider, which doesn't create a payment session with a third-party provider.
+    - The Manual System Payment Provider is available by default in Medusa and can be used to handle payments without a third-party provider. It allows you to mark the order as paid without requiring any additional actions from the customer.
+    - Make sure to configure the Manual System Payment Provider in your store's region. Learn more in the [Manage Region](!user-guide!/settings/regions#edit-region-details) user guide.
+
+---
+
 ## Stripe Example
 
 If you're integrating Stripe in your Medusa application and storefront, refer to the [Stripe guide](./stripe/page.mdx) for an example of how to handle the payment process using Stripe.

www/apps/resources/app/storefront-development/checkout/payment/stripe/page.mdx

@@ -250,6 +250,23 @@ const getPaymentUi = useCallback(() => {
 
 ---
 
+## Troubleshooting
+
+### Unknown Error for Zero Cart Total
+
+If your cart has a total of `0`, you might encounter an `unknown error` when trying to create a payment session.
+
+Stripe requires a non-zero amount to create a payment session. So, if your cart has a total of `0`, the error will be thrown on Stripe's side.
+
+In those cases, you can either:
+
+- Make sure the payment session is only initialized when the cart has a total greater than `0`.
+- Use payment providers like the Manual System Payment Provider, which doesn't create a payment session with a third-party provider.
+    - The Manual System Payment Provider is available by default in Medusa and can be used to handle payments without a third-party provider. It allows you to mark the order as paid without requiring any additional actions from the customer.
+    - Make sure to configure the Manual System Payment Provider in your store's region. Learn more in the [Manage Region](!user-guide!/settings/regions#edit-region-details) user guide.
+
+---
+
 ## More Resources
 
 - [Stripe's documentation](https://docs.stripe.com/).

www/apps/resources/app/troubleshooting/_sections/payment/zero-total.mdx

@@ -0,0 +1,31 @@
+If your cart has a total of `0`, you might encounter an `unknown error` when trying to create a payment session.
+
+## Why this Error Occurred
+
+Some payment providers, such as Stripe, require a non-zero amount to create a payment session. So, if your cart has a total of `0`, the error will be thrown on the payment provider's side.
+
+## Solutions
+
+### Initialize Payment Session Only for Non-Zero Totals
+
+Make sure the payment session is only initialized when the cart has a total greater than `0`. You can add a check before creating the payment session:
+
+```ts
+if (cart.total > 0) {
+  // TODO Initialize payment session
+}
+```
+
+### Use Manual System Payment Provider
+
+Use payment providers like the Manual System Payment Provider, which doesn't create a payment session with a third-party provider.
+
+The Manual System Payment Provider is available by default in Medusa and can be used to handle payments without a third-party provider. It allows you to mark the order as paid without requiring any additional actions from the customer.
+
+Make sure to configure the Manual System Payment Provider in your store's region. Learn more in the [Manage Region](!user-guide!/settings/regions#edit-region-details) user guide.
+
+---
+
+## Additional Resources
+
+- [Payment Providers](../../../commerce-modules/payment/payment-provider/page.mdx)

www/apps/resources/app/troubleshooting/payment/page.mdx

@@ -0,0 +1,11 @@
+import ZeroTotalError from "../_sections/payment/zero-total.mdx"
+
+export const metadata = {
+  title: `Payment Provider Errors`,
+}
+
+# {metadata.title}
+
+## Unknown Error for Zero Cart Total
+
+<ZeroTotalError />