WebDav fails with client certficates on Windows 7

Question

I have a SharePoint 2007 site on Windows Server 2003 R2 that is set up to require SSL/HTTPS and client certificates on the IIs Web App. Opening Document Libraries in Windows Explorer works fine from Windows XP IE6 clients. However, from Windows 7 (64bit) IE8 I get this generic, well known, error: Your client does not support opening this list with Windows Explorer.

Turning off the client certificiate requirement (but still requiring SSL/HTTP) makes it work, so it's not really related to SSL/HTTPS nor is it something fundamental missing in regards of WebDav support. However, I do need client certificates.

Any ideas?

Answer 1

I just went throught this a couple of months ago. You need to add the site to your trusted sites in IE. Then you need to add the certificate to your trusted root certificate store. You can do this by clicking on the certificate error in the address bar, viewing the cert, then install. Another thing, in Win7, webDav opens in Windows Explorer rather than in IE.

Answer 2

Ok, this was a bizzare edge case.

The problem is now identified as related to the Schannel Secure Channel security package in an enterprise scenario with more than one smart card.

Whenever two smart cards (or two certificate providers) are used, the Schannel fails with the following error:

A fatal error occurred when attempting to access the SSL client credential private key. The error code returned from the cryptographic module is 0x8009030d. The internal error state is 10003.

And that results in the generic error on the client side.

Regards,

Magnus