I have a wcf web service deployed inside the isapi folder of a sharepoint 2013.

Sometimes the web service go down and an iisreset seems to solve the problem.

The error message complains about a 'ntlm' authentication against a 'NTLM' authentication.

However I always log with the same user so the authentication problem seems strange to me.

Logs: SPSecurityContext: Get trust client failed with exception: System.IO.FileLoadException: Could not load file or assembly 'Microsoft.IdentityModel.Extensions, Version=, Culture=neutral, PublicKeyToken=69c3241e6f0468ca'...

Application error when access /_vti_bin/FileSystem.svc, Error=Provider type not defined. (Exception from HRESULT: 0x80090017)

Non-OAuth request. IsAuthenticated=True, UserIdentityName=, ClaimsCount=0

SPRequest.PreInitServer: UserPrincipalName=, AppPrincipalName= ,bstrAbsoluteRequestUrl=...

1 Answer 1


web.config change try :

<security mode="Transport">
<transport clientCredentialType="NTLM" />

OR in code try

client.ClientCredentials.Windows.AllowedImpersonationLevel = TokenImpersonationLevel.Impersonation;
  • I have no web.config in my wcf, sharepoint does all the work. Commented Sep 10, 2014 at 18:06

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