I got an answer from VMware and wanted to let you guys know:

"Yes that article is correct, you can avoid the 'Invalid Session Cookie' issue by utilizing NTLM authentication for Agent-Manager communications. To do so:

- Access the 'settings' table in the App Volumes database
- Add a row with the following values (or update the row if the key already exists):
key: "disable_agent_session_cookie"
value: "1"

The reason it's failing in 2.16 and not the older version you're using, is because the session cookie is a new feature of 2.14.

No there won't be an impact from disabling it. When it's disabled your users will be using NTLM to authenticate.

NTLM is recommended and it is how AV authenticates the VMs connecting to it. The fix mentioned above, which involved setting "disable_agent_session_cookie" to 1 in the SQL DB, does not disable the use of NTLM.

It disables the use of the session cookie. That means every connection between the VM and AV will go through an NTLM handshake process. The cookie is an optimization that can be disabled if there are problems like what you were seeing.

We create an authorized session for each computer based on a triplet of computer info (ex: computer name), VM info, and a unique session key. Only one unique session key is allowed to be valid at a time.

I've seen this issue previously, and the problem was caused by a combination of two behaviors in an environment:

1) vGPU use requiring a power cycle which, in turn, on AV side triggers generating a new session key
2) re-using the computer name which causes naming collisions with the newly generated session key (since only one can be valid at a time per computer name)."

Kind regards,

Markus