# HTTP response codes

Source: https://developer.avalara.com/restv1-to-restv2-refactor-guide/ayp7745504528137/

# HTTP response codes

Learn about HTTP response codes returned by AvaTax API calls and how to handle them.

When an AvaTax API call produces an error, it returns a standard HTTP response code.

Response codes between 400 and 499 are client errors and indicate an issue with the API call.

Response codes between 500 and 599 refer to internal errors within AvaTax. Each internal error is logged automatically and reported to the development team for triage.

If your program receives an HTTP response code between 400 and 499, follow these steps:

1.  Parse the error message using a JSON parser.

2.  Display a summary of the error to the user.

3.  Link the user to the documentation page that explains the error.

4.  Allow the user to modify their request or retry the action.