We are dealing with this error message for a lot of our users. Some of them are using the ThinClients and some are using the Horizon App. We didn't change anything in our environment, no recent updates, no pool recompose/re-deployment.
The work around has been moving the user's to PCOIP and that seems to work better but still some users cant connect with Blast or PCOIP. I've been working with VMware support all day and they can't find anything, since we have some users that are able to connect they don't consider this a system down so it has been hard to escalate.
VM Tools 11.2.0, build -16938113
VM Agent 7.5.0
App Volume 22.214.171.124
It may be a guess, but did you try to downgrade the Vmware Tools ?
Looking the matrix, for Agent 7.5.0, you should use Vmware Tools 11.0.5 or 10.3.10
You might try to update the Agent to 7.5.3.