How to troubleshoot IIS 7.5 401.2 Error?

Question

I am have been fighting this error in IIS 7.5 for sometime now, and no solution I find seems to help. As I understand it, a 401.2 error means that the browser and the site in IIS are using two different types of authentication.

I have two Web Services hosted in IIS 7.5. Web Service A makes a call to Web Service B. This is where the 401.2 error happens. Both Web Services have Windows Authentication Enabled with 401 Challenge. The only enabled provider on each is NTLM. The Web.Config for both services is set up to have

<authentication mode="Windows" />

Here is what the call from Web Service A to WebService B looks like:

   WebServiceB.Credentials = new System.Net.NetworkCredential("ValidUser", "ValidPW", "ValidDomain");
   var output = WebServiceB.DoSomething(input); //Throws 401 WebException

As far as I can tell, both the Web Services and IIS sites should be using Windows Authentication, and nothing but Windows Authentication, yet I continue to get these 401.2 errors. Why?

Are you using NTLM through a proxy? Perhaps try the solution documented here - http://support.microsoft.com/kb/253667 — clamchoda, Nov 01 '13 at 18:14

score 0 · Answer 1 · edited May 23 '17 at 12:21

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I guess it is related to double-hop issue. Pleae try with delegation of creditential to second call.

May be the following link help you. Please have a look at it.

How can I fix the Kerberos double-hop issue?

edited May 23 '17 at 12:21

Community

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answered Nov 01 '13 at 19:10

Ravi Vellanki

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score 0 · Accepted Answer · answered Nov 04 '13 at 14:04

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this turned out to be an issue with the way the user was configured with a third party software. Thank you for all of your responses.

answered Nov 04 '13 at 14:04

Dave

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This doesn't really seem like an answer to the problem. It's the lack of an answer. – bambams Aug 06 '14 at 21:12

How to troubleshoot IIS 7.5 401.2 Error?

2 Answers2