HTTP Status Code 494 – Request Header Too Large
Description
The HTTP status code 494 Request Header Too Large is a non-standard status code primarily used by specific server software, such as Nginx. It indicates that the server is unable to process the request due to the size of the request header fields being too large. This typically occurs when the client sends a header that exceeds the server’s configuration limits.
Examples
Example 1: Excessive Cookies
Suppose a client sends a request with an excessively large number of cookies, which causes the server to respond with a 494 status code:
GET / HTTP/1.1
Host: example.com
Cookie: sessionId=abc123; userPref=lightMode; cartItems=10; ... (many more cookies)
... (other headers)
In this example, the number of cookies and their combined size exceed the server’s acceptable limits, triggering the 494 response.
Example 2: Large Custom Header
A client sends a request with a very large custom header, leading to a 494 response:
GET /api/data HTTP/1.1
Host: example.com
X-Custom-Header: [a very long string exceeding server limits]
... (other headers)
Here, the custom header X-Custom-Header contains a payload that is too large for the server to handle, resulting in the server returning a 494 status code.
– The 494 status code is not part of the standard HTTP/1.1 status codes defined by the IETF but is used by some server software like Nginx.
– Understanding server configuration and limitations is crucial when dealing with this status code, as it often relates to server settings that dictate maximum allowable header sizes.
Example 3 Scenario
# Client sends a request example.
GET /example HTTP/1.1
Host: www.example.com
# Server Response
HTTP/1.1 494 494 Request Header Too Large
Date: Wed, 09 Oct 2024 23:09:02 GMT
Server: ExampleServer/1.0
Content-Type: application/json
{
"error": "Description of the error for 494"
}
Example 4 Scenario
# Client sends another example request.
POST /another-example HTTP/1.1
Host: www.example.com
# Server Response
HTTP/1.1 494 494 Request Header Too Large
Date: Wed, 09 Oct 2024 23:09:02 GMT
Server: ExampleServer/1.0
Content-Type: application/json
{
"error": "Detailed message for 494"
}
Summary
The 494 Request Header Too Large status code alerts clients that their request headers exceed the server’s constraints. This response is typically a result of the server’s configuration settings, which can often be adjusted by a server administrator to accommodate larger headers. Clients encountering this error may need to reduce the size of their request headers, such as by consolidating or compressing cookie data or by minimizing the use of large custom headers.
