kerberos sudenly stop working on an IIS server

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Hi,

for 6 month I have an application which use the kerberos delegation and works fine.

yesterday the kerberos delegation stop working and my users can't access the backend resources anymore!

I receive the standard KDC_ERR_BADOPTION error on the IIS server.

a netdiag command on my database server says:
Kerberos test. . . . . . . . . . . : Failed
Found DC '\\<dcserver>.<domain>.local' in domain '<domain>'.
[FATAL] Cannot lookup package Kerberos.
The error occurred was: (null)

why this problem occurs now?
what could appends?

I have checked the setspn entries and the AD to make sure there is no changes related to the service account I'm using and there is no changes. all the required setspn entries are present, and the account is trusted for delegation.

For the moment I switch to basic authentication to solve the issue.
But the system must works fine using Kerberos.

does the problem is related to my database server or my IIS server?
any idea?

thanks for your help.

Jerome.



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