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The HyperText Transfer Protocol (HTTP) 501 Not Implemented server error response code indicates that the server does not support the functionality required to fulfill the request. This is the appropriate response when the server does not recognize the request method and is not capable of supporting it for any resource. The only request methods that servers are required to support (and therefore that must not return this code) are GET and HEAD.

Notes:

  • A 501 error is not something you can fix, but requires a fix by the web server you are trying to access.
  • A 501 response is cacheable by default.

Status

501 Not Implemented

Specifications

Specification Title
RFC 7231, section 6.6.2: 501 Not Implemented Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content

Browser compatibility

The information shown below has been pulled from MDN's GitHub (https://github.com/mdn/browser-compat-data).

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
501Chrome Full support YesEdge Full support YesFirefox Full support YesIE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesEdge Mobile Full support YesFirefox Android Full support YesOpera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support

Document Tags and Contributors

Last updated by: mdnwebdocs-bot,