You receive the “vSphere client could not connect with the vCenter Server” error message when you attempt to connect to the Virtual Center using a remote VMware vSphere Client
I received this error message after a system restart to complete the installation of the some Windows updates. Fortunately it was nothing major – just 2 services that had failed to start. Just ensure that the VMware VirtualCenter Management Webservices and VMware VirtualCenter Server services are both ‘Started’