When you access Oracle VM manager via browser, you may see SSL error like this:
It's not because of your browser's security setting, it's about your VM manager security policy. So you have to look back your VM manager. Try to find a configuration file like the following:
[root@ovmm ~]# vi /u01/app/oracle/ovm-manager-3/domains/ovm_domain/config/config.xml
Then add a line under <ssl> to allow more encryption algorithms for clients.
Try to open Oracle VM manager administration page again.
It should be OK this time.