The OVM console is not working on clients after OVM Manager was installed

99% the root cause is the tightvnc.
Uninstall the tightvnc:

> yum -erase tightvnc

Then, install the tightvnc-java on OVM Manager Server (you can download from https://oss.oracle.com/oraclevm/manager/RPMS/tightvnc-java-1.3.9-3.noarch.rpm).

Guess what, your browser will be glad to open, now, the OVM Console.

Legend: OVM=Oracle Virtual Machine