How to resolve SSL error "A specified logon session does not exist. It may already have been terminated. (Exception from HRESULT: 0x80070520)" on IIS

When attempting to bind an SSL certificate to a website, you get the error :  "A specified logon session does not exist. It may already have been terminated. (Exception from HRESULT: 0x80070520)"

The most likely cause of this error is a private key not being installed for the SSL certificate.

This means that the "Mark Exportable" check box was not selected when importing the SSL certificate.  To resolve this issue, re-import the SSL certificate from MMC certificate console and make sure the "Mark Exportable" check box is selected.