When the SQLDiag utility runs on a server in a Windows Cluster and at least one computer in this cluster group has a 15-character-long name, the SQLDiagutility would fail. Additionally, you receive the following error message in the SQLDiag output logs:
Error enumerating virtual servers. Is your SQL Server instance clustered? There are no instances of version 12 on this computer. Function result: 87. Message: The parameter is incorrect.
The issue was first fixed in the following cumulative update of SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. We recommend that you download and install the latest cumulative updates for SQL Server: