I spent more than 4 hours to resolve the following error.

“The HTTP request is unauthorized with client authentication scheme ‘Anonymous’. The authentication header received from the server was ‘NTLM’.”

I got this error when I tried to write a simple call “GetList(“Site Pages”) ” from List.ASMX service.

TO RESOLVE Do the following steps, after adding web reference to the service on a simple console application. using “http://[YOUR HOST HERE]/_vti_bin/lists.asmx”

1.  Add the following line

ServiceReference1.ListsSoapClient list = new ServiceReference1.ListsSoapClient();

list.ClientCredentials.Windows.AllowedImpersonationLevel = TokenImpersonationLevel.Impersonation;

 2. Also make sure in the app.config file you have the following.

<security mode="TransportCredentialOnly">
      <transport clientCredentialType="Ntlm" proxyCredentialType="Ntlm" realm=""/>
      <message clientCredentialType="UserName" algorithmSuite="Default"/>
</security>
 

I hope this helps, if you have the same error.