Unable to logon to OWA using forms-based authentication
When a user enters valid credentials, they are taken to a blank page https://ExchCASServerName.domain.com/owa/auth.owa. But if they enter bad credentials, it just redirects to the logon page and asked them to logon again.
"Microsoft Exchange Forms-Based Authentication service." need to be started.
This service was not running and it was set to "Automatic (Delayed Start)" changing it to just "Automatic" allowed it to start properly.