When I had that issue it was due to a corrupt CalData.pgo.
However, before removing any file, make sure that the dates on your LEFs are current, and also review that the services are running with the expected account in the Windows services console services.msc.
If all the above is as expected, I would contact Qlik Support.
Did you have the services on separate servers already before upgrading, or are you scaling out as part of the upgrade?
Check that the "URL" to the QVS is correct in the settings, so that the QMC isn't trying to configure a QVS that doesn't exist. It's under QMC > System > Setup > QlikView Servers. Click the QVS node and make sure the URL is correct, like qvp://theqvsserver/.
Just wanted to check because I've just upgraded to November 2018 and had the same issue.
I resolved it by stopping the services, creating a new QlikView windows account on the server, which I added to the administrators group and the QV Administrators group, and then setting each service (all five) to logon using that new account.
I then restarted the services and the QV server started to work!
I hope you have solved your issue, but if not... give it a go.