HRESULT 0x801901F5 (HTTP_E_STATUS_NOT

Status / error code:

Category:

Constant name:

Source:

Facility:

Operating System:

Description:

The server returned HTTP 501 Not Implemented because it lacks required functionality.

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HTTP_E_STATUS_SERVER_ERROR	HTTP_E_STATUS_BAD_GATEWAY

HTTP_E_STATUS_NOT_SUPPORTED

HTTP_E_STATUS_NOT_SUPPORTED maps to HTTP 501 Not Implemented. The server does not support the functionality required to fulfill the request, commonly an unimplemented request method or extension.

What to check

Identify the request method, protocol feature, extension, or content coding that the server rejected.
Compare the client behaviour with the endpoint capability and version documentation.
Distinguish 501 from 405: 501 means the server lacks the capability; 405 means the method is known but disallowed for this particular resource.

RFC 9110: 501 Not Implemented

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