Symptoms

The client was trying to configure AAD in their environment and ran into a problem when trying to add an OAuth resources in K2. When he clicked the System > Management > Security > Forms > Manage OAuth Resources form, they saw an "Host Unknown" error.

 

Diagnoses

There was a bunch of repairs and reconfiguring that happened before logging the ticket, so we are not quite sure what lead to the problem, but looking at the decrypted K2HostServer.exe.config, we founds that there was a connection string that was still pointing to an old machine and that was the unknown host that caused the error.
 

Resolution

We decrypted the K2HostServer.exe.config file, updated the connection string to point to the current K2HostServer, made a backup of the "old" K2HostServer.exe.config and replaced it with the updated one. After restarting the K2HostServer, there were still issues with opening the K2 Designer and the K2 smartforms runtime sites. We re-configured K2 smartforms just to make sure that the connection strings were updated and we cleared the browser cache. After that, we were able to browse to the "Manage OAuth Resources" form again.