SQL Server 2008 Std SP1 CU2 (10.0.2714.0) on Windows Server 2008 Std SP2.

I have multiple instances running on this server. With SSMS I can browse and connect to other named instances on this server but I cannot see hostname\MSSQLSERVER and attempts to connect to this instance fail with this error:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 25 - Connection string is not valid) (Microsoft SQL Server, Error: 87)

I have cheked:

  • Server service for MSSQLSERVER is running
  • Firewall is off
  • Connections are enabled in Configuration Manager
  • Have tried 1433 and dynamic ports
  • I can see the port the instance is listening on
  • I am running SSMS as admin

1 Answer 1


MSSQLSERVER is the instance name of the default instance. When connecting to the default instance you just need to use the hostname, you don't need to qualify the connection with the instance name.

  • Goodness... something so simple! Now I'm one step closer. I just need to find out what the login is next! Thanks for that. Jan 11, 2012 at 17:14
  • Hahaha! Afraid you're on your own for that one :)
    – squillman
    Jan 11, 2012 at 17:23

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