As a best practice, It is suggested to plan for manual reboot for vcenter.
Mentioned, if there are any task on the vcenter those will cancelled.
I suggested, that remove all the connected session to vcenter.
stop the vcenter services and reboot the server.
once its back verify the same.
Thanks & Regards
Dharshan S
VCP 4.0,VTSP 5.0, VCP 5.0