I've got a desktop system which has been showing error messages in the Event Viewer ever since the upgrade to Windows 8.1 Update. It's an error in EnhancedStorage-EhStorTcgDrv that says "A TCG Command has returned an error". The error is with the "AuthenticateSession" command.
Doing a bunch of research shows that this error involves SSD encryption. However, this is for a gaming PC with no personal information on it. There's no need for Bitlocker or anything of that sort on it. So I'm not entirely sure why it's sending that command in the first place other than if it's using the "Opal" / Microsoft eDrive spec for automatic encryption. The SSD I'm using (Plextor PX-M5M) does fully support the Opal specification, but I do not have a TPM, and as this is a desktop PC it doesn't support Connected Standby, two features that previously were requirements for automatic encryption on Windows 8.1. Did something change with regards to these requirements in Windows 8.1 Update?
I guess the really important question is... is this actually a message I should be worried about? It's listed in Event Viewer as critical. Can it just be ignored instead?
For what it's worth, my first thought was actually that the SSD or the mSATA slot it is installed in were the cause. However, both of those have been swapped out as part of my troubleshooting, and that hasn't solved anything.