After recently upgrading a Windows based installation of IGEL Universal Management suite from v. 6.04 to 6.05, we ran into an interesting issue, where no users could authenticate. This included both Active Directory based users, along with local IGEL users.
As you can see, the GUI opens without issue, it is when we try to login that we get the error.
I first started down the firewall troubleshooting path, but quickly realized that I was connecting on localhost, so there was no firewall in the way (at least there shouldnt be). To make a long story short, during the upgrade process it appears that the IGEM RMGUIserver service (windows) had crashed, and failed to restart.
A quick bounce of the service, and we were back in action for both AD and local users. I have since uninstalled the latest version of UMS, installed 6.04, and went through the upgrade process again to determine if it was a bug with the upgrade process, however things proceeded as expected, and I was able to login. Looked to be an issue with my local system.
Anyway, if you get the error in UMS of could not connect to host, check the RMGUIserver service.