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I have successfully configured Windows Server 2008 Enterprise SP2 with SQL Server 2008 Enterprise SP2 all 64 bit, however when I tried to access this particular SQL Server 2008 DB instance from another SQL Server 2008 SSMS in another Windows Server 2008 it failed ?

what I did is to disabled the IPv6 IP address using the regedit but still the problem hasn't been fixed even after restart ?

I have enabled the named piped as well but still no luck ?

any help please ?

Here's the error message: "

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: 26 - Error Locating Server/Instance Specified) (Microsoft SQL Server, Error: -1)


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How are you connecting? Via IP address directly? If so, you need to enable TCP/IP for that specific IP in the Configuration Manager. Also disabling IPv6 in Windows itself is a bad idea, even if you don't use it. Windows uses IPv6 localhost addresses internally, and that'll break stuff that is very hard to track down again. – Mojah Mar 17 '11 at 7:37
Is this a named instance or the default instance? – mrdenny Mar 17 '11 at 8:20
it is named instance, I install two in one single DB server physical box while still maintaining port 1433 for both instances as default and simplicity – Server System Specialist Mar 18 '11 at 4:01
up vote 2 down vote accepted

An assortment of possibilities here.

More common reasons include

  • Firewall blocking UDP 1434
  • SQL Browser not running or needing to be restarted

Less common:

  • Misconfiguring named instance to listen on 1433
  • Bad connection strings
  • Name resolution issues (zone from DNS removed)
share|improve this answer
many thanks for the reply, in Windows server firewall I am confused of which application to UNBLOCK ? do I have to select both TCP and UDP port 1433 ? – Server System Specialist Mar 18 '11 at 4:03
and then restart the SQL Server DB instance (both) as well as the SQL Server browser service only not the whole server ? – Server System Specialist Mar 18 '11 at 4:03
Hi Albert, SQL Server Browser listens in on UDP port 1434 (allowing you to connect to named instances). If it isn't running you can still connect to a SQL instance if this is a default SQL instance running on 1433 (or if you designate the port manually) - but if not, check out the BOL topic "How to: Configure a Windows Firewall for Database Engine Access" for more details. If this is a SQL Server Browser issue, just restarting that service (or making sure it is started) should be enough. You don't need to restart the SQL Server instance too and whole server - just the browser service. – Joe Sack Mar 18 '11 at 11:26
ah cool, thanks for the explanation. – Server System Specialist Mar 21 '11 at 1:42

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