Symptom
When connecting to SQL Server, whether from the ODBC DSN or another method, you may experience all or part of the following error message:
An error has occurred while establishing a connection to the server. When connecting to SQL Server this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
Note: These steps resolve issues with an ODBC DSN that cannot be completely configured.
1) Verify that the database server name is correct. In the ODBC DSN, the Server field is populated with this information.
2) Verify that the instance name specified is correct, and that the instance exists on the database server. For example, if the database server name is SERVER, and the instance name is SQLEXPRESS, the Server field in the ODBC DSN should be:
SERVER\SQLEXPRESS
3) Verify that the database server is reachable from the client computer trying to connect. To test this, try to ping the server from the client by both name and IP address.
4) Verify that the SQL Server Browser service is started on the database server.
5) If there is a firewall enabled on the database server, verify that UDP port 1434 is entered as an exception.
After verifying each of these steps the error referenced in this article should no longer appear.
An error has occurred while establishing a connection to the server. When connecting to SQL Server this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
Resolution
To resolve the issue, follow the steps below.Note: These steps resolve issues with an ODBC DSN that cannot be completely configured.
1) Verify that the database server name is correct. In the ODBC DSN, the Server field is populated with this information.
2) Verify that the instance name specified is correct, and that the instance exists on the database server. For example, if the database server name is SERVER, and the instance name is SQLEXPRESS, the Server field in the ODBC DSN should be:
SERVER\SQLEXPRESS
3) Verify that the database server is reachable from the client computer trying to connect. To test this, try to ping the server from the client by both name and IP address.
4) Verify that the SQL Server Browser service is started on the database server.
5) If there is a firewall enabled on the database server, verify that UDP port 1434 is entered as an exception.
After verifying each of these steps the error referenced in this article should no longer appear.
