The HTTP request is unauthorized with client authentication scheme 'Negotiate'. The authentication header received from the server was 'Negotiate,NTLM'

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In the course of enabling WCF services using Windows authentication, you may have hit this error. A Bing search will show that there are a myriad of reasons as to why this might occur.

However, before you get bogged down in the complexities of WCF bindings and IIS metadata, there ‘may’ be a simple fix. If the client and service are on the same machine and you experience the aforementioned error, check out this article:

https://blogs.msdn.com/b/distributedservices/archive/2009/11/10/wcf-calling-wcf-service-hosted-in-iis-on-the-same-machine-as-client-throws-an-authentication-error.aspx

This was infuriatingly difficult to track down but once found, I couldn’t understand why it wasn’t top of the search engine results.

Hopefully this will give the matter a little more press.

Later.

Brad