A specified logon session does not exist. It may already have been terminated (Exception: 0x80070520)
What?! Well apparently the solution lies in the import step. I had to mark the .PFX file as exportable, which I didn't. Correct way to do this:
- Within IIS7 click on Server > Server Certificates
- Import... Select the Certificate File (.pfx), optional password and mark the Allow this certificate to be exported.
- Now you can choose the certificate on Site > Bindings..
- Select the 443 Binding > Edit OR Add a new 443 Binding
- Select the SSL certificate and click OK. You are ready.