ASP.NET - web parts - Asked By Halo Bright on 10-May-11 03:41 AM

Hi,
When i try to run a simple webpart this error gets propping up. I dont know what it means.

"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) "

Im not using any kind of backend support for this. Pls help.

Reena Jain replied to Halo Bright on 10-May-11 04:11 AM
hi,

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible.

Hope this will help you
Sahil Kumar replied to Halo Bright on 10-May-11 04:43 AM

Hi,

You will get this error when you will not able to connect to sql server with your credentials.

You got check below issue.

1)    The sql server you are trying to connect should have mixed mode enable. That is connection should be made by windows authentication and sql server authentication also. You can enable this from

Start programs - > sql server - > configuration Tools -> sql server configuration tool

Just enable settings from there

2)    The credentials you are trying to connect should have access on database.


Hope this will help you.
Riley K replied to Halo Bright on 10-May-11 05:05 AM

Check into the steps to resolve this error.

1) SQL Server should be up and running.

Go to All Programs >> Microsoft SQL Server 2008 >> Configuration Tools >> SQL Server Configuration Manager >> SQL Server Services, and check if SQL Server service status is “Running”.

In addition, ensure that your remote server is in the same network. Run “sqlcmd -L” in your command prompt to ascertain if your server is included in your network list. 

I have confronted numerous situations when these nerve-wracking errors crop up, and most of the time when I try to troubleshoot I notice that SQL Server services are neither running nor installed. If SQL Server is not installed as default instance SQL Server Browser should be running together with it; we will explore this further in Topic 5.

2) Enable TCP/IP in SQL Server Configuration

When two or more SQL Servers are connected across network they do all communication using TCP/IP. The default port of SQL Server installation is 1433. This port can be changed through SQL Server Configuration Manager. TCP/IP should be enabled for SQL Server to be connected.

Go to All Programs >> Microsoft SQL Server 2008 >> Configuration Tools >> SQL Server Configuration Manager >> Select TCP/IP

Right Click on TCP/IP >> Click on Enable

You must restart SQL Server Services for all the changes to take effect. Right click and go to menu properties to select location where default port of SQL Server can be changed.

3) Open Port in Windows Firewall

Windows Firewall is very efficacious in protecting the Operating system from all sorts of malicious attacks. By default, many of the ports and services are refrained from running by firewall. Time and again, SQL Server ports are not open in firewall as well. All the ports on which SQL Server is running should be added to exception and firewall should filter all the traffic from those ports. As described, by default SQL Server runs on port 1433, but if default port is changed then the new port should be added to exception. If SQL Server has named instance (another instance besides default instance) is installed, SQL Server browser should also be added to the exception, as described in Step 7.

Go to Control Panel >> Windows Firewall >> Change Settings >> Exceptions  >> Add Port

Make the following entries in popup “Add a Port” and click OK.
Name : SQL
Port Number: 1433
Protocol: Select TCP

4) Enable Remote Connection

Enabling remote connection is another important, yet oft-neglected step that is frequently missed by database administrators while setting up SQL Server. If this feature is turned off SQL Server will function smoothly on local machine, but it will let another server connect to it remotely. By default this feature is ON in SQL Server 2008.

Right click on the server node and select Properties.

Go to Left Tab of Connections and check “Allow remote connections to this server”

5) Enable SQL Server Browser Service

If SQL Server is not installed as default instance but instead installed as named instance and also if there is no specific TCP/IP port configured, it will give rise to the error that is being discussed in this article. If SQL Server Browser service is enabled, it will allow the server to be connected through dynamic TCP/IP port. Enabling this service is a one-time process, as on enabling it once it will apply to all the instances installed on the same server.

Go to All Programs >> Microsoft SQL Server 2008 >> Configuration Tools >> SQL Server Configuration Manager >> SQL Server Browser

Right Click on SQL Server Browser >> Click on Enable

6) Create exception of sqlbrowser.exe in Firewall

As elucidated in Step 6, sqlbrowser service needs to be enabled for named instance. Windows Firewall may prevent sqlbrowser.exe to execute. So, it is imperative to add exception for the same in windows firewall.

Search for sqlbrowser.exe on your local drive where SQL Server is installed. Copy the path of the sqlbrowser.exe like C:\Program Files\Microsoft SQL Server\90\Shared\sqlbrowser.exe and create the exception of the file in Firewall, as delineated in Step 3.

7) Recreate Alias

It is getting quite common to create alias of SQL Server and use it in application. This will ensure that in future if any physical SQL Server has to be moved, it will not be required to change any code or connection string. You can simply create alias with the same name pointing to different SQL Server and it will start working instantaneously. I have observed that a couple of times due to internal error while recreating alias this error was fixed.

Go to All Programs >> Microsoft SQL Server 2008 >> Configuration Tools >> SQL Native Client 10.0 Configuration >> Aliases

Delete the alias that is giving problem and recreate it with identical parameters.

I have tried my best to include all the methods of fixing this error and if I have missed any, please leave a comment and I will be very glad to include them here. I have put in my effort to encompass this issue in one article that needs to be refereed when any connection error comes up.

Jitendra Faye replied to Halo Bright on 10-May-11 05:07 AM
For this error check following things-

1. Make sure your database engine is configured to accept remote connections
• Start > All Programs > SQL Server 2005 > Configuration Tools > SQL Server Surface Area Configuration
• Click on Surface Area Configuration for Services and Connections
• Select the instance that is having a problem > Database Engine > Remote Connections
• Enable local and remote connections
• Restart instance

2. Check the SQL Server service account
• If you are not using a domain account as a service account (for example if you are using NETWORK SERVICE), you may want to switch this first before proceeding

3. If you are using a named SQL Server instance, make sure you are using that instance name in your connection strings in your ASweb P.NET application
• Usually the format needed to specify the database server is machinename\instancename
• Check your connection string as well


<connectionStrings>

<add name=”SampleConnectionString” connectionString=”Data Source=machinename\instancename;Initial Catalog=AdventureWorks;Integrated Security=SSPI;Min Pool Size=5;Max Pool Size=60;Connect Timeout=30″ providerName=”System.Data.SqlClient”/>

</connectionStrings>

4.You may need to create an exception on the firewall for the SQL Server instance and port you are using

• Start > Run > Firewall.cpl
• Click on exceptions tab
• Add the sqlservr.exe (typically located in C:\Program Files (x86)\Microsoft SQL Server\MSSQL.x\MSSQL\Binn), and port (default is 1433)
• Check your connection string as well

5. If you are using a named SQL Server instance, make sure you are using that instance name in your connection strings

6. Check SQLBrowser; check that it is running. You may also need to create an exception in your firewall for SQLBrowser.

7. Check that you have connectivity to the SQL Server. Note what you are using to connect: machine name, domain name or IP address? Use this when checking connectivity. For example if you are using myserver
• Start > Run > cmd
•netstat -ano| findstr 1433
•telnet myserver 1433
•ping -a myserver

for more detail follow this-
http://www.sqlmusings.com/2009/03/11/resolving-a-network-related-or-instance-specific-error-occurred-while-establishing-a-connection-to-sql-server/