The HTTP 408 status code stands for "Request Timeout". It is a client error response indicating that the server closed the connection because the client did not send a complete request within the server's timeout period.

When is HTTP 408 Used?

  • When the client takes too long to send the request headers or body.
  • When the server is under heavy load and terminates inactive connections to free up resources.
  • When network latency or connectivity issues prevent the request from being completed in time.

How Does It Work?

When a client sends a request, the server allocates resources to handle it. If the client fails to complete the request within the allowed time, the server sends a 408 Request Timeout and closes the connection.

Common Causes of HTTP 408 Errors

  • Slow or unstable network connections.
  • Client-side timeouts where the client doesn't send the full request in time.
  • High server load causing delays in processing.
  • Misconfigured timeout settings on either the client or the server.

Example Scenarios

  • A mobile app with a poor internet connection tries to submit a form.
  • A client script sends a large file upload but takes too long to send the entire payload.
  • A web application connects to an API with aggressive timeout settings.

Example

Client Request (Incomplete Request Due to Slow Network)

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

(The client starts sending the request but doesn't complete it within the server's timeout period.)

Server Response (408 Request Timeout)

    
        HTTP/1.1 408 Request Timeout
        Content-Type: application/json

        { "error": "The server timed out waiting for the request to complete." }

Best Practices for Handling HTTP 408

  • Optimize network connections: Ensure stable and reliable connectivity.
  • Adjust timeout settings: Configure reasonable timeout values on both client and server.
  • Implement retry logic: Allow automatic retries for idempotent requests like GET.
  • Monitor network performance: Track latency and error rates to proactively address issues.

Retrying Requests After HTTP 408

  • Safe methods like GET can be retried automatically.
  • Non-idempotent methods like POST should be retried with caution to avoid duplicated operations.

Summary

HTTP 408 indicates that the server closed the connection because the client did not send the full request in time. It often occurs due to network issues, client-side delays, or server timeout settings. Retrying the request or optimizing the network can help resolve this issue.