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 SQL 2012: Connection error 26

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Starting Member

2 Posts

Posted - 2013-02-02 : 13:13:42
Hi everyone,

I am working locally on new laptop (windows 8 x64) with SQL Express 2012 SP1 x64, and I get the following connection 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: 26 - Error Locating Server/Instance Specified)".

Kindly notice that service sqlserver is running and that shared memory, TCP/IP, Named Pipes are all enabled.

Sometimes connection is successful but only for a while.
Usually I get the connection error.

Any ideas how to resolve this issue?

Thanks in advance

James K
Master Smack Fu Yak Hacker

3873 Posts

Posted - 2013-02-02 : 15:28:03
See if you are connecting to the correct instance. Normally for SQLExpress, the Server Name should be (local)\SQLEXPRESS or SERVERNAME\SQLEXPRESS.
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Starting Member

2 Posts

Posted - 2013-02-02 : 15:49:30
I do connect to right instance.
Sometimes connection succeeds for a while and then is lost.

Thanks anyway
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Posting Yak Master

160 Posts

Posted - 2013-02-05 : 23:55:05
Detailed explanation is given below taken from blogs.msdn

Every time client makes a connection to SQL Server named instance, we will send a SSRP UDP packet to the server machine UDP port 1434. We need this step to know configuration information of the SQL instance, e.g., protocols enabled, TCP port, pipe name etc. Without these information, client does know how to connect the server and it fails with this specified error message.

In a word, the reason that we get this error message is the client stack could not receive SSRP response UDP packet from SQL Browser. It's easy to isolate the issue. Here are the steps:
1) Make sure your server name is correct, e.g., no typo on the name.
2) Make sure your instance name is correct and there is actually such an instance on your target machine. [Update: Some application converts \\ to \. If you are not sure about your application, please try both Server\Instance and Server\\Instance in your connection string]
3) Make sure the server machine is reachable, e.g, DNS can be resolve correctly, you are able to ping the server (not always true).
4) Make sure SQL Browser service is running on the server.
5) If firewall is enabled on the server, you need to put sqlbrowser.exe and/or UDP port 1434 into exception.

Once you are done the steps, you should not see this error message anymore.
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Jolly Den
Starting Member

1 Post

Posted - 2013-02-06 : 07:22:17
Here is the complete guide to learn sql:
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