> ## Documentation Index
> Fetch the complete documentation index at: https://docs.guile.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Invalid Payment Method Source

> The appointment payment source cannot be authorized through Guile

## Cause

The appointment uses a payment source that cannot be authorized through Guile, for example an external cash or peer-to-peer source when a Guile card hold is
required.

## Fix

Use a Guile-saved card payment source, then
[authorize an appointment payment](/api-reference/appointments/authorize-an-appointment-payment)
(or create the appointment again with that source).

## Retry safety

Not retryable

## Raised by

These operations can return this problem:

* [Create an appointment](/api-reference/appointments/create-an-appointment)
* [Authorize an appointment payment](/api-reference/appointments/authorize-an-appointment-payment)

## Example

```json theme={null}
{
 "type": "https://docs.guile.app/problems/invalidPaymentMethodSource",
 "title": "Invalid Payment Method Source",
 "status": 422,
 "detail": "The appointment uses a payment source that cannot be authorized through Guile."
}
```