pablitobs
I assume the contrib was installed to /opt/...
You do not tell us what else you did to get the main domain pointing at the /opt/joomla install location.
Whatever else you did, is most likely the source of your problem.
It will probably be simpler to move the /opt install to an ibay, modify the joomla config settings appropriately, and then point your main domain to the ibay using the server manager Domains panel.