This error indicates that the browser being used does not have a valid MPKI Admin ID certificate installed, or the certificate is not functioning correctly.
The admin ID will be located in the browser that was used to download the admin ID certificate. The first thing to check is to see if the browser being used has a valid admin ID certificate installed. The following steps can be used to access the web browser being used to check for a valid Admin ID.
Firefox: Menu > Options > Advanced > Certificates > View Certificates > Your Certificates.
Internet Explorer: Menu > Internet Options > Content > Certificates > Personal.
Chrome: Menu > Settings > Show Advanced Settings > Manage Certificates > Personal.
Safari: Applications > Utilities > Keychain Access > Certificates.
If the admin ID is not present, it may be located in another computer or web browser. The admin ID can be moved from one browser/computer to another. See the following link: Migrating your Admin credentials to a new browser.
If a valid admin ID is not available, this error can be resolved by doing a free replacement. See the following link: How to replace a Managed PKI for SSL administrator ID. This is a free process to create a new admin ID certificate.
An expired admin ID can be renewed by completing the steps in the following link: How do I renew my Managed PKI for SSL Administrator ID. The renewed admin ID should be installed to the same browser that will be used to access the MPKI account.