The HyperText Transfer Protocol (HTTP) 412 Precondition Failed client error response code indicates that access to the target resource has been denied. This happens with conditional requests on methods other than GET or HEAD when the condition defined by the If-Unmodified-Since or If-None-Match headers is not fulfilled. In that case, the request, usually an upload or a modification of a resource, cannot be made and this error response is sent back.


412 Precondition Failed


Specification Title
RFC 7232, section 4.2: 412 Precondition Failed Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests

Browser compatibility

The information below has been pulled from MDN's GitHub (

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes Yes Yes Yes Yes Yes
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support Yes Yes Yes Yes Yes Yes Yes

See also

Document Tags and Contributors

 Contributors to this page: RayannTedds, haroldfredshort, fscholz, zemadz, AlexeyVasilievE, teoli
 Last updated by: RayannTedds,