# Source: https://docs.klarna.com/resources/developer-tools/error-handling/error-codes-and-messages.md

# Error codes and messages

Klarna's API relies on standard HTTP response codes to signal the success or failure of a request. When an API call is successful, Klarna will respond with a 2xx status code and when the API call fails Klarna will respond with a 4xx or 5xx status code together with a response body containing an error object with the error code, an array of error messages and a unique correlation id to be used to identify the request.

- `2xx` codes indicate success.
- `4xx` codes indicate an an error on the client side (e.g., missing parameters or failed transactions).
- `5xx` codes indicate server-side errors.

In order to deep dive on error make sure you check `PSP logs dashboard` or `Klarna Developers Logs`app in Merchant Portal for error messages to see what's exactly wrong in the details.