client error RFC 9110
HTTP 408 Request Timeout
Client took too long to send the request — server gave up waiting.
What it means
The server was expecting more data from the client and it never arrived within the timeout window. This is client-side (bad upload connection, dropped WiFi) — NOT the same as 504 Gateway Timeout, which is server-to-upstream. Most modern browsers just retry silently, so end users rarely see 408.
When servers send it
- •Client started a POST body upload and stopped mid-way
- •Keep-Alive connection went idle past the server's timeout
- •Slow network dropped the upload before completion
What the client does
Retries. Modern browsers retry automatically. Idempotent methods (GET, PUT, DELETE) are safe; POST retries need care.
Common causes
- •Slow network on the client side
- •Large file upload timing out
- •Proxy or CDN between client and server closing the connection
How to fix it
- 1.Increase server request timeout for large uploads
- 2.Use chunked/resumable upload for files larger than a few MB
- 3.Retry the request from the client
Similar codes
504 Gateway Timeout server error
A gateway or proxy timed out waiting for a response from the upstream server.
503 Service Unavailable server error
Server is temporarily unable to handle the request — overloaded or down for maintenance.
400 Bad Request client error
Server cannot process the request due to a client-side error — malformed syntax, invalid JSON, missing required fields.
401 Unauthorized client error
Authentication is required and either missing or invalid — the client is not identified.
403 Forbidden client error
Server understood who you are but refuses to authorize the request — permission denied.
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