4xx Client error
HTTP 412 Precondition Failed
A condition in the request headers, such as If-Match or If-Unmodified-Since, evaluated to false. Typically the resource changed since the client last read it, and the server refuses the change so it doesn’t overwrite someone else’s update.
//_01 Uptime checks
Is 412 up or down for a monitor?
Uptimecheck HTTP monitor
Default settings
Down. It is outside the default 200–399 range, so a monitor reports an outage once a second check confirms it. If 412 is the answer you expect from that URL, add it to the monitor’s expected status codes.
Is it down? checker
Free, at /is-it-down/
Up. The checker counts any answer below 500 as the site answering: a 412 comes from a server that is running.
//_02 Causes and fixes
Why you see 412 and what to do
Typical causes
- A conditional update to a resource that changed in the meantime.
If you run the site
- Nothing to fix: it is doing its job. Clients should fetch the latest version and try again.
If you’re a visitor
- Reload and try 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 412 mean?
A condition in the request headers, such as If-Match or If-Unmodified-Since, evaluated to false. Typically the resource changed since the client last read it, and the server refuses the change so it doesn’t overwrite someone else’s update.
Does an uptime monitor count 412 as down?
Down. It is outside the default 200–399 range, so a monitor reports an outage once a second check confirms it. If 412 is the answer you expect from that URL, add it to the monitor’s expected status codes.
Downtime is obsolete.
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