I just got that a few minutes ago because I had to kill vSphere Client after it stopped working. And when I restarted it, I couldn’t open any console on my VMs. Well more precisely I could open them but a warning  on the top of the window was saying:

The VMRC Console has Disconnected. Trying to reconnect

Finally I figured out that I still had a process running called vmware-vmrc.exe. Just kill this process also, make sure to have vSphere closed when killing it, and then restart the vSphere client and consoles should work again.