A Specified Logon Session Does Not Exist. It May Already Have Been Terminated Posted on by Webmaster IT Support Forum › Forums › Web Servers › IIS › Troubleshooting › A Specified Logon Session Does Not Exist. It May Already Have Been Terminated Tagged: Certificates This topic contains 0 replies, has 1 voice, and was last updated by Webmaster 2 months, 3 weeks ago. Author Posts November 20, 2018 at 11:05 am #2382 WebmasterKeymaster When trying to add a certificate to an IIS website Binding, you can get this error: Edit Site Binding There was an error while performing this operation. Details: A specified logon session does not exist. It may already have been terminated. (Exception from HRESULT: 0x80070520) This error occurs because there’s an issue with the certificate you are trying to use or it’s associated intermediate certificate. To fix this, delete the certificate then reinstall it using the following instructions: In IIS, go to Server Certificates and delete the certificate from there Check the Certificates MMC to ensure it’s removed from there too Check that it’s not available in the IIS website’s Bindings In IIS, go to Server Certificates and Import the PFX file from there Try to assign the IIS Binding again, you shouldn’t get the specified logon session does not exist error anymore Author Posts You must be logged in to reply to this topic.