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501 Not Implemented

The HyperText Transfer Protocol (HTTP) 501 Not Implemented server error response code indicates that the request method is not supported by the server and cannot be handled. The only 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).

Feature Chrome Edge Firefox Internet Explorer Opera Safari
Basic support Yes Yes Yes Yes Yes Yes
Feature Android webview Chrome for Android Edge mobile Firefox for Android IE mobile Opera Android iOS Safari
Basic support Yes Yes Yes Yes Yes Yes Yes

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https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/501