What does HRESULT 0x803D001E (WS_E_SERVER_REQUIRES_NTLM_AUTH) mean?

WS_E_SERVER_REQUIRES_NTLM_AUTH

WS_E_SERVER_REQUIRES_NTLM_AUTH is a Windows Web Services API HRESULT. It means that the remote endpoint rejected the offered authentication scheme and requires NTLM authentication.

What to check for WS_E_SERVER_REQUIRES_NTLM_AUTH

• Verify the target host, connection settings and identity context used by the client process.
• Check whether the service and network policy permit NTLM for this endpoint.
• Do not disclose integrated credentials to an endpoint whose identity is not verified.

Microsoft documentation

Diagnostic discriminator: Confirm that the endpoint itself issued the NTLM challenge and that policy permits NTLM for this service. A successful connection followed by this result is an authentication negotiation problem, not endpoint unavailability.