# API not found error

The API Gateway finds the corresponding `Registered API` based on the user's specified `HTTP Specification`, which includes `HTTP Protocol` `HTTP Method` `URI` and other parameters. If your API is published in a non-`Release` environment, you need to carry the `X-Gw-Stage` request header in the `HTTP request header`. If `API not found error` occurs, please check the following checklist:

* Whether the API request protocol, Method, URI, etc. are consistent with the API specification
* Check whether the API has been published to the corresponding Stage
* Check the correctness of the X-Gw-Stage parameter in the HTTP request header, this value should be set corresponding to the environment name in which the API is published.