# API error handling

Source: https://developer.avalara.com/services-calculation-en/errors/api_error_handling/

# API error handling

When an AvaTax 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 they indicate a mistake in an API call. Response codes between 500 and 599 refer to internal errors within AvaTax itself. 

**Code**

**Description**

200

The request has succeeded.

400

Bad Request - The server could not understand the request due to invalid syntax.

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 exists.

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.

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