# Status Codes

Every API **MUST** use the appropriate [HTTP Status Codes](https://github.com/for-GET/know-your-http-well/blob/master/status-codes.md) to communicate the result of a request operation.

Every API designer, implementer and consumer **MUST** understand the semantic of the HTTP Status Code she is using.

At a minimum everyone **MUST** be familiar with the semantics of ["Common" HTTP Status Codes](https://github.com/for-GET/know-your-http-well/blob/master/status-codes.md#common).

## Example

## Use Codes 4xx or 5xx to Communicate Errors

The 4xx range concerns errors in the API Consumer/Client side, while 5xx range concerns errors in the upstream/backend service or the API implementation.

A request:

```
GET /orders/1234 HTTP/1.1
...
```

resulting in the **200 OK** response when the requested resource (as identified by request URI) couldn't be found:

```
HTTP/1.1 200 OK
Content-Type: application/json
...


{
    "code": "NOT_FOUND_ERR_CODE"
    "message" "Order 1234 wasn't found"
}
```

is **not acceptable**.

Instead

```
HTTP/1.1 404 Not Found
...
```

should be returned.

## Recommended Reading

* [How to Think About HTTP Status Codes](https://www.mnot.net/blog/2017/05/11/status_codes)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://adidas.gitbook.io/api-guidelines/rest-api-guidelines/protocol/use-appropriate-status-codes.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.