I'm quite new to certificates but I managed to install a new one in my Win2012R2 Server. But now I try to install this certificate with TMSHttpConf.exe and get an error:
A specified logon session does not exist. It may already have been terminated.
That is an error that is usually caused by a misconfiguration in the certificate itself. Maybe the certificate misses some relevant information, or the certificate chain is not recognized. It's a very generic error message, unfortunately, that is usually solved by reissuing the certificate with slightly different data.