# HTTP responses
<a name="api-making-requests-response"></a>

All Network Firewall API actions include JSON-formatted data in the response.

Here are some important headers in the HTTP response and how you should handle them in your application, if applicable.

**HTTP/1.1**  
This header is followed by a status code. Status code 200 indicates a successful operation.   
Type: String

**x-amzn-RequestId**  
A value created by Network Firewall that uniquely identifies your request, for example, `K2QH8DNOU907N97FNA2GDLL8OBVV4KQNSO5AEMVJF66Q9ASUAAJG`. If you have a problem with Network Firewall, AWS can use this value to troubleshoot the problem.   
Type: String

**Content-Length**  
The length of the response body in bytes.  
Type: String

**Date**  
The date and time that Network Firewall responded, for example, Wed, 07 Oct 2019 12:00:00 GMT.  
Type: String

## Error responses
<a name="api-making-requests-error-response"></a>

If a request results in an error, the HTTP response contains the following values:
+ A JSON error document as the response body
+ A `Content-Type` header
+ The applicable 3xx, 4xx, or 5xx HTTP status code

The following is an example of a JSON error document:

```
HTTP/1.1 400 Bad Request
x-amzn-RequestId: b0e91dc8-3807-11e2-83c6-5912bf8ad066
x-amzn-ErrorType: ValidationException
Content-Type: application/json
Content-Length: 125
Date: Mon, 26 Nov 2012 20:27:25 GMT

{"message":"1 validation error detected: Value null at 'TargetString' failed to satisfy constraint: Member must not be null"}
```