The page requires a valid SSL client certificate

Your client certificate is untrusted or invalid. A Secure Sockets Layer (SSL)client certificate is used for identifying you as a valid user of the resource.

Please try the following:

Contact the site administrator to establish client certificate permissions.

If you already have a valid client certificate, use your Web browser's security features to ensure that your client certificate is installed properly. (Some Web browsers refer to client certificates as browser or personal certificates.)

Change your client certificate and click the Refresh button, if appropriate.

HTTP Error 403.16 - Forbidden: Client certificate is ill-formed or is not trusted by the Web server.
Internet Information Services (IIS)

Technical Information (for support personnel)

Go to Microsoft Product Support Services and perform a title search for the words HTTP and 403.

Open IIS Help, which is accessible in IIS Manager (inetmgr), and search for topics titled About Certificates, Using Certificate Trust Lists, Enabling Client Certificates, and About Custom Error Messages.