Request Timeout

Overview

408 Request Timeout means the server waited for a complete request from the client, exceeded its time limit, and closed the connection. The cause is the client sending the request line, headers, or body too slowly.

Unlike 504 Gateway Timeout, where internal or upstream processing is slow, the key distinction of 408 is that the side sending the request (the client) is slow.

When it happens

• It is returned when a client on a slow or unstable network fails to send the request body in time.
• It can also occur when the server times out an idle keep-alive connection that a connection pool opened in advance.

Request / Response example

POST /upload HTTP/1.1
Host: example.com
Content-Length: 5000000

(client stalls; body never fully arrives within the server's timeout)

HTTP/1.1 408 Request Timeout
Connection: close
Content-Type: text/html

<h1>Request Timeout</h1>

In code

# server waits this long for the client to send the request body
client_body_timeout 12s;
client_header_timeout 12s;  # slow clients -> 408

Notes

• By spec a 408 response often comes with Connection: close, signaling the client to retry on a fresh connection.
• Browsers frequently retry the request automatically once after receiving a 408.
• When a server safely rejects TLS early-data (0-RTT) requests, 425 Too Early is used rather than 408.

Related status codes

Related headers

Specification