title: SQL Server Express fails to connect without any useful error information after ASP.NET MVC Web App user login
body: <p>I am using Visual Studio 2013 Update 4, I have an ASP.NET MVC Web Application which is using Entity Framework 6.1.1.</p>
  
  <p>When I try to run my web application, it fails to load with an error.</p>
  
  <p>In the console I get the same error repetitively:</p>
  
  <pre><code>A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
  A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
  A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
  A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
  A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
  A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
  </code></pre>
  
  <p>In the web browser I get this error:</p>
  
  <pre><code>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. 
  
  SQLExpress database file auto-creation error: 
  
  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:
  
  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: http://go.microsoft.com/fwlink/?LinkId=160102. 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.
  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.
  
  
  Source Error: 
  
  An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
  
  Stack Trace: 
  
  
  [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, Action`1 wrapCloseInAction) +1900630
     System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) +545
     System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean withFailover) +452
     System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover) +198
     System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout) +923
     System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance) +324
     System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData) +646
     System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions) +459
     System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup, DbConnectionOptions userOptions) +38
     System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal&amp; connection) +800
     System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +143
     System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +21
     System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry) +141
     System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry) +252
     System.Data.SqlClient.SqlConnection.Open() +130
     System.Web.Management.SqlServices.GetSqlConnection(String server, String user, String password, Boolean trusted, String connectionString) +75
  
  [HttpException (0x80004005): Unable to connect to SQL Server database.]
     System.Web.Management.SqlServices.GetSqlConnection(String server, String user, String password, Boolean trusted, String connectionString) +125
     System.Web.Management.SqlServices.SetupApplicationServices(String server, String user, String password, Boolean trusted, String connectionString, String database, String dbFileName, SqlFeatures features, Boolean install) +89
     System.Web.Management.SqlServices.Install(String database, String dbFileName, String connectionString) +29
     System.Web.DataAccess.SqlConnectionHelper.CreateMdfFile(String fullFileName, String dataDir, String connectionString) +386
  
  Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.5.27.0
  </code></pre>
  
  <p>So I tried to connect to the database using SQL Server Management Studio using the connection string taken from the Properties windows in Visual Studio:</p>
  
  <pre><code>Data Source=(LocalDb)\v11.0;AttachDbFilename=C:\Users\Aaron\Desktop\AbcBankSolution\AbcBankWebApplication\App_Data\aspnet-AbcBankWebApplication-20150203085459.mdf;Initial Catalog=aspnet-AbcBankWebApplication-20150203085459;Integrated Security=True
  </code></pre>
  
  <p>This gives the following error:</p>
  
  <pre><code>The value's length for key 'data source' exceeds it's limit of '128'
  </code></pre>
  
  <p>Which is odd considering it is only 15 in length...</p>
  
  <p>Finally, in Visual Studio, I can connect and refresh the database in the Server Explorer window, so I really don't know what is going on...</p>
  
  <p>How can I fix this problem?</p>