4xx Client error Non-standard · used by nginx
HTTP 499 Client Closed Request
A code nginx writes in its log when the client closed the connection before nginx sent a response. It is never sent to anyone: by then nobody is listening. Many 499s usually mean the application is slow, and clients or load balancers give up waiting.
Not defined in any RFC: nginx only writes it to its own log.
//_01 Uptime checks
Is 499 up or down for a monitor?
Uptimecheck HTTP monitor
Default settings
Never received: it is a line in nginx’s log, not an answer. If the server is too slow for a monitor, the check times out (after 10 seconds by default, adjustable up to 30) and counts as down.
Is it down? checker
Free, at /is-it-down/
Never received: if the site is too slow to answer, the checker reports a timeout and the site as down.
//_02 Causes and fixes
Why you see 499 and what to do
Typical causes
- Slow pages or API calls, where the visitor, an app or a load balancer times out first.
- Visitors closing the tab or navigating away during a slow request.
If you run the site
- Find the slow requests in the log (response times next to the 499s) and speed them up.
- Check that the timeouts of load balancers in front of nginx are longer than your slowest legitimate request.
If you’re a visitor
- Nothing to do: you will never see this code.
Know the moment your site stops answering as it should
An Uptimecheck monitor requests your page as often as every minute, checks the status code against the ones you expect, confirms a failure with a second check and then alerts you.
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Questions
What does HTTP 499 mean?
A code nginx writes in its log when the client closed the connection before nginx sent a response. It is never sent to anyone: by then nobody is listening. Many 499s usually mean the application is slow, and clients or load balancers give up waiting.
Does an uptime monitor count 499 as down?
Never received: it is a line in nginx’s log, not an answer. If the server is too slow for a monitor, the check times out (after 10 seconds by default, adjustable up to 30) and counts as down.
Downtime is obsolete.
Set up your first monitor in under a minute, or look around the live demo first.
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