Error: Failed to join site, failed to register the server machine. Unable to access SDE datastore
When attempting to join a newly installed instance of ArcGIS for Server 10.1 to an existing site, the following error is returned:
"Failed to join site, failed to register the server machine. Unable to access SDE datastore."
To join the existing ArcGIS Server site, the new machine must be able to connect to and validate any datastore or database connections. If it cannot connect to and validate the database connections, it does not join the existing ArcGIS Server site.
Solution or Workaround
To connect to and validate database connections, the native client for the database must be installed.
Download the native client for the database used on the ArcGIS Server site. This native client can be obtained from the Esri Customer Care Portal.