HTTP 408 — Request Timeout

What 408 actually means

The connection was opened but the request never arrived complete within the server's patience — a slow upload on a bad connection, or an idle keep-alive connection being reaped. It is a 4xx because the server is blaming the client for being slow, though in practice the network is usually at fault. Note it is the opposite of 504: here the client was slow to send, not the upstream slow to answer.

Common causes

• A slow or dropping connection during a large upload
• The server closing an idle keep-alive connection, which some clients report as 408
• A client that opened a connection and sent nothing
• A too-aggressive `client_body_timeout` or `client_header_timeout` on the server
• A Slowloris-style protection kicking in against genuinely slow clients

If you're just trying to view the page

1. Retry — this is often transient
2. Check your connection, especially on mobile data or a congested Wi-Fi network
3. For large uploads, try a wired connection, or upload a smaller file to test
4. Close other applications saturating your upload bandwidth

If it's your site

1. Raise `client_body_timeout` and `client_header_timeout` in Nginx, or the equivalent in your server, if legitimate users on slow links are being cut off
2. Support resumable or chunked uploads for anything large rather than relying on one long request
3. Send `Connection: close` with the 408 so the client does not try to reuse a dead connection
4. Distinguish idle-keep-alive reaping from genuine timeouts in your logs; the first is normal and the second is not

Reference

Status code

408

Reason phrase

Request Timeout

Category

4xx — Client Error

Defined in

RFC 9110 §15.5.9