# API error handling

Source: https://developer.avalara.com/goods-calculation-en/errors/api_error/

When an AvaTax Brazil API call produces an error, it responds using the standard [HTTP error response codes](https://en.wikipedia.org/wiki/List_of_HTTP_status_codes). Response codes between 400 and 499 are called **Client Errors**, and indicate a mistake in an API call. Response codes between 500 and 599 refer to internal errors within AvaTax Brazil itself.

Code

Description

400

Bad Request - refer to internal errors within TaxCompliance

401

Authentication credentials were missing or incorrect.

403

The request is denied because you do not have permission to make this alteration.

404

The URL requested is invalid or the resource requested does not exist.

429

The user has sent too many requests in a given amount of time ("rate limiting").

500

The server has encountered a situation it doesn't know how to handle

503

The server is not ready to handle the request.