AWS RDS SQL Server from EC2 ASP.NET IIS7

Question

I have done the following -

• I set up a new EC2 instance running Windows Server 2008 with IIS7.

• I set up a new RDS Instance running SQL Server 2008 R2.

• I have configured the Security Group for the RDS server to allow SQL Server connections on port 1433 from the EC2 instance.

• On the EC2 instance I can connect to the RDS SQL Database by creating a User or System ODBC Connection from Windows. I can also connect from my own computer with SQL Management Studio.

When I try to start up my .NET Web Application I get this 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) 

This is my connection string, I am using Entity Framework and an edmx , Database first .

<add name="EntitiesName" connectionString="metadata=res://*/Models.Model1.csdl|res://*/Models.Model1.ssdl|res://*/Models.Model1.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=myrdsserver.rds.amazonaws.com;initial catalog=VPN;User Id=userid;Password=password;Persist Security Info=True;MultipleActiveResultSets=True;&quot;" providerName="System.Data.EntityClient" />

I've tried everything in the following links but nothing works to allow me to connect.

aws ec2 could not open a connection to sql server

entity framework 5 and amazon rds underlying prodiver failed to open

can't connect to rds instance from ec2 instance

UPDATE: I created a Windows .NET Forms application that uses the same connection string and Entity Framework and it works. I ran it from the same EC2 instance. It seems that the main difference here is that IIS is not involved with the Windows Form application. I'm not sure how that is keeping the Web application from working.

Here is the stack trace from the web page:

[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) +6573870
   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) +717
   System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean withFailover) +6600312
   System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover) +219
   System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout) +6602662
   System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance) +6603203
   System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData) +942
   System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions) +1162
   System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions) +72
   System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) +6606457
   System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) +103
   System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection) +2102
   System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection) +116
   System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection) +1079
   System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +6610951
   System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry) +233
   System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry) +278
   System.Data.SqlClient.SqlConnection.Open() +239
   Hangfire.SqlServer.SqlServerStorage.CreateAndOpenConnection() +49
   Hangfire.SqlServer.SqlServerStorage..ctor(String nameOrConnectionString, SqlServerStorageOptions options) +279
   Hangfire.SqlServerStorageExtensions.UseSqlServerStorage(IGlobalConfiguration configuration, String nameOrConnectionString) +80
   MyWebApplication1.Startup.Configuration(IAppBuilder app) +39

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor) +0
   System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments) +76
   System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) +211
   System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters) +35
   Owin.Loader.<>c__DisplayClass1.<LoadImplementation>b__0(IAppBuilder builder) +341
   Microsoft.Owin.Host.SystemWeb.OwinAppContext.Initialize(Action`1 startup) +996
   Microsoft.Owin.Host.SystemWeb.OwinHttpModule.InitializeBlueprint() +119
   System.Threading.LazyInitializer.EnsureInitializedCore(T& target, Boolean& initialized, Object& syncLock, Func`1 valueFactory) +241
   Microsoft.Owin.Host.SystemWeb.OwinHttpModule.Init(HttpApplication context) +108
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +530
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +304
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +404
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +475

[HttpException (0x80004005): Exception has been thrown by the target of an invocation.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +12618692
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +159
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +12458309

Answer 1

I found out what this was. Everything I did in my question was correct and working. I had another connection string in the application Startup that was being called for another service. That connection string wasn't updated so it wasn't opening the connection.