WCF Client Inner Exception: "The Security Support Provider Interface (SSPI) negotiation failed."

Creating a WCF Client in Visual Studio 2010, I struggled with this error.  I was running as the currently logged on user and the service was as well so this made no sense to me.  I found that this entry in the client app.config was the culprit:

<userPrincipalName value="MYDOMAIN\MyUsername" />

Simply deleting these 3 lines allowed me to test the client.

Let me know if this helped you!

Comments (21)

  1. Pramod Desai says:


    it helped a lot, after searching for an hour

  2. baba says:

    yes same error and it helped

  3. Chinese says:

    Thank you vary much!!!

  4. Well it did the trick… not sure how and why. But thanks!

  5. Michi says:

    Cool thanks, helped a lot 🙂

  6. Yaniv says:

    Thank you very much. It helped.

  7. Hendra Pratama says:

    Yes, great… Thanks. Do you have more details explanation about this problem?

  8. Jeff Sanders says:

    Yes.  You want to run in the context of the service not a particular user.

  9. dar3d says:

    You bet it did and saved me a lot of time. Thank you so much 🙂

  10. Akshay says:

    Thanks! It helped 🙂

  11. Alex says:

    Thank you! I didn't even see those 3 lines.

  12. Vibhu says:

    Thanks.. it really saved lot of time

  13. Andrew R says:

    Thanks, its my issue as well 🙂

  14. WCF learner says:

    you have saved my time man.. Thanks

  15. It worked like a charm after the alteration you suggested. Thanks buddy!

  16. Fred Bloggs says:

    Thanks that got my test application working but I was determined to make it work with those three lines left in.

    So this is what I did (on Windows 7 Pro logged on as a domain user));

    1) I needed to find out what my User Principal Name (UPN) was. A bit of Googling gave me this gem. Open a cmd prompt and run;

    whoami /upn

    This gave me; fred.bloggs@xyz.com

    2) But I'd also read that I needed to prefix this with my domain name. I ran whoami again without the /upn switch;

    That gave me xyzfred.bloggs, so my domain is xyz.

    So putting it all together;


        <userPrincipalName value="xyzfred.bloggs@xyz.com />


    It works!!

    Hope that helps someone out 🙂

  17. Ak says:

    Thanks Fred. It worked for me 🙂

  18. JM says:

    Great!!! It works!! Thank you..

  19. gitere says:

    thanks alot

  20. Murali Mohan Parvatha says:

    Simple trick saved my time 🙂
    Thanks for the post

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