This is likely due to the console URL is locked. Run command "emctl status oms -details" to verify (look for the line starting with "OMS Console" in the output).
You should be able to access the console over https.
I found the solution myself.
We need to unlock the console to use Non-ssl url and then bounce the OMS.
emctl secure unlock -console
It is good to know that you found a solution without any help