I found this suggestion:
For VMware vCenter Appliance 5.x
Restart virtual center server through the web interface.
- Log in to the vCenter Server Appliance’s VAMI (Virtual Appliance Management Interface) at http://<IP/hostname of VC>:5480
- Select the Summary tab under vCenter Server.
- Click Stop beside vCenter Server to stop the process.
- Click Start beside vCenter Server to start the process
But when I try to log into the interface it simply says page can not be displayed. Gonna try to reboot the VM.