title: Error. SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified
body: <p>I'm getting above error when I tried to create an account on default "My ASP.NET Application". I installed fresh copies of Ms SQLServer 2008 and Visual Studio 2010 version on Windows 7 OS. Just to test DB Connection withASP.net I tried to create account using My ASP.NET Application and I got following error details. Im new to asp.net development. So I dont have much clear idea how to fix this error.  </p>
  
  <ul>
  <li>All Sql services are running. </li>
  <li>All Protocols for MSSQLSERVER is enabled.</li>
  </ul>
  
  <blockquote>
    <p>Server Error in '/' Application. 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) Description: An unhandled exception occurred during the execution of the current web request.
    Please review the stack trace for more information about the error and
    where it originated in the code.</p>
  </blockquote>
  
  <p>SQLExpress database file auto-creation error:</p>
  
  <p>The connection string specifies a local Sql Server Express instance using a database location within the application's App_Data directory. The provider attempted to automatically create the application services database because the provider determined that the database does not exist. The following configuration requirements are necessary to successfully check for existence of the application services database and automatically create the application services database:</p>
  
  <p>If the application is running on either Windows 7 or Windows Server 2008R2, special configuration steps are necessary to enable automatic creation of the provider database. Additional information is available at: <a href="http://go.microsoft.com/fwlink/?LinkId=160102" rel="nofollow">http://go.microsoft.com/fwlink/?LinkId=160102</a>. If the application's App_Data directory does not already exist, the web server account must have read and write access to the application's directory. This is necessary because the web server account will automatically create the App_Data directory if it does not already exist.</p>
  
  <p>If the application's App_Data directory already exists, the web server account only requires read and write access to the application's App_Data directory. This is necessary because the web server account will attempt to verify that the Sql Server Express database already exists within the application's App_Data directory. Revoking read access on the App_Data directory from the web server account will prevent the provider from correctly determining if the Sql Server Express database already exists. This will cause an error when the provider attempts to create a duplicate of an already existing database. Write access is required because the web server account's credentials are used when creating the new database.
      Sql Server Express must be installed on the machine.
      The process identity for the web server account must have a local user profile. See the readme document for details on how to create a local user profile for both machine and domain accounts.</p>
  
  <p><strong>Stack Trace:</strong></p>
  
  <pre><code>[SqlException (0x80131904): 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)]
     System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +5063578
     System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning() +234
     System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity) +341
     System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, SqlConnection owningObject) +129
     System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, TimeoutTimer timeout) +270
     System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, TimeoutTimer timeout, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +195
     System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +232
     System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +5077239
     System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup) +31
     System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +76
  </code></pre>
  
  <hr>
  
  <pre><code>[HttpException (0x80004005): Unable to connect to SQL Server database.]
  System.Web.Management.SqlServices.GetSqlConnection(String server, String user, String password, Boolean trusted, String connectionString) +137
     System.Web.Management.SqlServices.SetupApplicationServices(String server, String user, String password, Boolean trusted, String connectionString, String database, String dbFileName, SqlFeatures features, Boolean install) +94
     System.Web.Management.SqlServices.Install(String database, String dbFileName, String connectionString) +27
     System.Web.DataAccess.SqlConnectionHelper.CreateMdfFile(String fullFileName, String dataDir, String connectionString) +395
  </code></pre>
  
  <hr>
  
  <p>Web.config:</p>
  
  <pre><code>    &lt;?xml version="1.0"?&gt;
  
  &lt;!--
    For more information on how to configure your ASP.NET application, please visit
    http://go.microsoft.com/fwlink/?LinkId=169433
    --&gt;
  
  &lt;configuration&gt;
    &lt;connectionStrings&gt;
      &lt;add name="ApplicationServices"
         connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true"
         providerName="System.Data.SqlClient" /&gt;
    &lt;/connectionStrings&gt;
  
    &lt;system.web&gt;
      &lt;compilation debug="true" targetFramework="4.0" /&gt;
  
      &lt;authentication mode="Forms"&gt;
      &lt;forms loginUrl="~/Account/Login.aspx" timeout="2880" /&gt;
      &lt;/authentication&gt;
  
      &lt;membership&gt;
      &lt;providers&gt;
        &lt;clear/&gt;
        &lt;add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="ApplicationServices"
           enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false"
           maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10"
           applicationName="/" /&gt;
      &lt;/providers&gt;
      &lt;/membership&gt;
  
      &lt;profile&gt;
      &lt;providers&gt;
        &lt;clear/&gt;
        &lt;add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="ApplicationServices" applicationName="/"/&gt;
      &lt;/providers&gt;
      &lt;/profile&gt;
  
      &lt;roleManager enabled="false"&gt;
      &lt;providers&gt;
        &lt;clear/&gt;
        &lt;add name="AspNetSqlRoleProvider" type="System.Web.Security.SqlRoleProvider" connectionStringName="ApplicationServices" applicationName="/" /&gt;
        &lt;add name="AspNetWindowsTokenRoleProvider" type="System.Web.Security.WindowsTokenRoleProvider" applicationName="/" /&gt;
      &lt;/providers&gt;
      &lt;/roleManager&gt;
  
    &lt;/system.web&gt;
  
    &lt;system.webServer&gt;
       &lt;modules runAllManagedModulesForAllRequests="true"/&gt;
    &lt;/system.webServer&gt;
  &lt;/configuration&gt;
  </code></pre>