All HTTP status codes
4xx Client Error
Nginx-specific (non-standard)
499 Client Closed Request
Nginx-specific code: the client closed the connection before the server could respond.
What it means
HTTP 499 is a non-standard Nginx-specific status code indicating that the client closed the connection while Nginx was processing the request. Most often seen in slow-backend scenarios where the user navigates away.
When it's used
Logged by Nginx when a user clicks away or closes their browser before a slow backend responds.
Common causes
- User navigated away during slow page load
- AJAX request cancelled by client
- Mobile app put in background mid-request
- Aggressive client-side timeouts
How to fix it
- Speed up backend response times to reduce abandonment
- Implement request cancellation handling on the server
- Monitor for spike patterns indicating UX issues
- Consider this informational, not a server bug
Example response
(No response sent — client disconnected)
SEO impact
Indirect signal — high 499 rate suggests slow pages, which hurts Core Web Vitals.