Error 0x80070520 “A specified logon session does not exist” when binding a certifate in IIS 7 20 July, 2012IISadmin I had a problem when using a certificate ( for ADFS) on IIS 7. This certificate once been used on IIS 6 and TMG 2010 server and it works fine. This means there is no problem with the certificate itself. To reproduce the steps : Open the IIS MMC open the Site Bindings add a HTTPS binding Select this certificate from the certificates drop down list, and click OK. Then you get the follow error: A specified logon session does not exist. It may already have been terminated. (Exception from HRESULT: 0x80070520) In my case, the solution is : remove the certificate from IIS Import the certificate using the Certificates MMC snap-in Choose the correct certificate in IIS manager Disclaimer : The author reserves the right not to be responsible for the topicality, correctness, completeness or quality of the information provided.