3xx Redirection
HTTP 304 Not Modified
The answer to a conditional GET or HEAD request (with If-None-Match or If-Modified-Since): the copy the client already has is still current, so the server sends no body and the client uses its cached copy. It saves bandwidth and makes repeat visits faster.
Defined in RFC 9110, section 15.4.5(opens in a new tab)
//_01 Uptime checks
Is 304 up or down for a monitor?
Uptimecheck HTTP monitor
Default settings
Up. By default an Uptimecheck HTTP monitor accepts 200–399 as up, so a 304 counts as up. With a keyword check, the page must also contain the word you set.
Is it down? checker
Free, at /is-it-down/
Up: the checker counts any answer below 500 as the site answering.
//_02 Causes and fixes
Why you see 304 and what to do
Typical causes
- A browser or CDN revalidating a cached page, image, script or style sheet.
If you run the site
- If visitors see old content after an update, check that the ETag or Last-Modified value changes when the content does, and what Cache-Control says.
If you’re a visitor
- If a page looks out of date, force a reload (Shift and reload) to fetch it again.
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 304 mean?
The answer to a conditional GET or HEAD request (with If-None-Match or If-Modified-Since): the copy the client already has is still current, so the server sends no body and the client uses its cached copy. It saves bandwidth and makes repeat visits faster.
Does an uptime monitor count 304 as down?
Up. By default an Uptimecheck HTTP monitor accepts 200–399 as up, so a 304 counts as up. With a keyword check, the page must also contain the word you set.
Downtime is obsolete.
Set up your first monitor in under a minute, or look around the live demo first.
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