The latest vSphere Upgrade Saga happened a week or so after my upgrade to vSphere 6.5. VMware vCenter just up and died on me. I looked at everything and eventually had to call in VMware Support. That is a rare action for me these days, but it is nearly impossible to debug vCenter without their help.
I had entered vNetwork Distributed Switch h-e-double hockey sticks! A broken vNetwork Distributed Switch (vDS) makes for a bad day for anyone.