# Troubleshooting and list of error codes

## Working  with errors

This section captures a list of common HTTP errors you might encounter and possible solutions to fix them.

| HTTP Error Code | Error Text | Reason | Possible Fix |
|  --- | --- | --- | --- |
| `HTTP 400` | Hotel reservation has transaction message of the wrong type | Possible reasons are, you are trying to:  - acknowledge a message that is no longer the latest for that given reservation  - acknowledge a message using the wrong endpoint. For example, acknowledging a modification via the new reservations endpoint. | Query the Reservations API again to fetch the latest message. Use the `POST OTA_HotelResNotif` endpoint to acknowledge a new reservation or use the `POST OTA_HotelResModifyNotif` endpoint to acknowledge a modification or a cancellation. |
| `HTTP 403` | Access denied for hotel | Possible reasons are, you are trying to:  - retrieve reservations for a property with the wrong hotel ID.  - send requests using machine account that do not have access to the specified hotel ID.  - retrieve reservations for a property which is no longer connected to your interface.  | Make sure to specify the correct hotel ID or check your machine account credentials. You can check which property IDs are connected to which machine accounts under ‘**Machine Accounts**’ in the Provider Portal. In addition, you can check the connection status of properties in the ‘**Properties**’ tab in the Provider Portal, using the property ID.  |
| `HTTP 404` | Hotel reservation was not found | This error can only occur while requesting a reservation by specifying the reservation ID in the request. Possible reasons are:  - The specified reservation does not exist.  - The reservation does exist, but the property is no longer connected to the provider. | The second scenario is very unlikely and the only possibile fix is to retrieve the reservation using the extranet. |
| `HTTP 409` | Response token '*token*' for hotel reservation '*ID*' does not match. please pull again." | This message implies that there were changes to the reservation details since you last retrieved the message. You can see this message only if the feature *OTA hotel reservation response token* (`ota_res_response_token`) is on. You can turn it on by using the [Provider portal](https://connect.booking.com/feature_management). | You must retrieve the reservation details again by specifying the reservation ID in the `OTA_HotelResNotif` or `OTA_HotelResModifyNotif` call. When acknowleding such messages, make sure to copy and paste both the `<HotelReservationID>` elements from the `GET` response. |
| `HTTP 410` | Hotel reservation is no longer available for delivery | This error can only occur while trying to retrieve a very old reservation by specifying the reservation ID in the request. | Check if the queried reservation ID is correct. Try querying a different reservation message by its ID. |
| `HTTP 500` | Internal server error | Possible reason may be that Booking.com systems are experiencing temporary outage. | Try calling the endpoint after some time. |