412 Precondition Failed - HTTP | MDN
developer.mozilla.org › en-US › docsHTTP security. Content Security Policy (CSP) HTTP Public Key Pinning (HPKP) HTTP Strict Transport Security (HSTS) Cookie security; X-Content-Type-Options; X-Frame-Options; X-XSS-Protection; Mozilla web security guidelines; Mozilla Observatory; HTTP access control (CORS) HTTP authentication; HTTP caching; HTTP compression; HTTP conditional ...