Weird exception when acceding database from web api project

Question

I am suddenly getting the following exception when trying to query the database

Application: 2014-03-27T20:56:01  PID[15096] Error       Error Getting user with id : 885151 Exception : System.Data.Entity.Core.EntityException: The underlying provider failed on Open. ---> System.Data.SqlClient.SqlException: 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: TCP Provider, error: 0 - An attempt was made to access a socket in a way forbidden by its access permissions.) ---> System.ComponentModel.Win32Exception: An attempt was made to access a socket in a way forbidden by its access permissions
Application:    --- End of inner exception stack trace ---
Application:    at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
Application:    at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
Application:    at System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean withFailover)
Application:    at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover)
Application:    at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout)
Application:    at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance)
Application:    at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData)
Application:    at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
Application:    at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
Application:    at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
Application:    at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
Application:    at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
Application:    at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
Application:    at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
Application:    at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
Application:    at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
Application:    at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
Application:    at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
Application:    at System.Data.SqlClient.SqlConnection.Open()
Application:    at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.<Open>b__38(DbConnection t, DbConnectionInterceptionContext c)
Application:    at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext](TTarget target, Action`2 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)
Application:    at System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open(DbConnection connection, DbInterceptionContext interceptionContext)
Application:    at System.Data.Entity.Core.EntityClient.EntityConnection.<Open>b__2()
Application:    at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1.<Execute>b__0()
Application:    at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
Application:    at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation)
Application:    at System.Data.Entity.Core.EntityClient.EntityConnection.Open()
Application:    --- End of inner exception stack trace ---
Application:    at System.Data.Entity.Core.EntityClient.EntityConnection.Open()
Application:    at System.Data.Entity.Core.Objects.ObjectContext.EnsureConnection(Boolean shouldMonitorTransactions)
Application:    at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
Application:    at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.<GetResults>b__5()
Application:    at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
Application:    at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
Application:    at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0()
Application:    at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
Application:    at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
Application:    at System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.<GetElementFunction>b__2[TResult](IEnumerable`1 sequence)
Application:    at System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.ExecuteSingle[TResult](IEnumerable`1 query, Expression queryRoot)
Application:    at System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute[TResult](Expression expression)
Application:    at System.Data.Entity.Internal.Linq.DbQueryProvider.Execute[TResult](Expression expression)
Application:    at System.Linq.Queryable.SingleOrDefault[TSource](IQueryable`1 source)
Application:    at ServerMapping.Dal.GetUser(String externalID)
Application:    at TasteItWebSite.Controllers.LoginApiController.Get(String id)

The thing is that its not all the time... sometimes it works but sometimes it does not. Its a webapi project which connects to an sql azure db using EF6.1

Why is this happening?

Answer 1

This is definitely a basic error showing that you are unable to connect to SQL Server. Usually, with Entity Framework, this means the config file is not set up properly.

Answer 2

I can think of two reasons.

1. If the machine accessing the database is in Azure and has its IP address changing, then you have to whitelist the IP in the Azure SQL database.

2. We've seen this where I work - same error. Azure SQL says there can and will be transient errors when executing queries. Here is a link with some more information: SQL Azure Database retry logic