Azure Sql and Azure Web App loosing connection - azure

Question

I run a web application on Azure and it connects with Azure Sql.
This has worked without any problems for a few years now.
But today I have started to get the following message:
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.
Problem is, that I can refresh, and sometimes it disappears, and sometimes it appears again. We haven't deployed anything for over a week, so does not seem to be related to that. App and Db are located at the same Azure hosting center.
Azure portal states there are no problems or know issues with anything, so what should I be looking for.
Any help is greatly appreciated.
The full stack trace
[Win32Exception (0x80004005): A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond]
[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: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)]
System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, DbConnectionPool pool, String accessToken, Boolean applyTransientFaultHandling) +821
System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions) +332
System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions) +38
System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) +497
System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) +89
System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection) +426
System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection) +78
System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection) +191
System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +154
System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +21
System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry) +90
System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry) +209
System.Data.SqlClient.SqlConnection.Open() +96
System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.<Open>b__36(DbConnection t, DbConnectionInterceptionContext c) +10
System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch(TTarget target, Action`2 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed) +72
System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open(DbConnection connection, DbInterceptionContext interceptionContext) +359
System.Data.Entity.Core.EntityClient.EntityConnection.<Open>b__2() +55
System.Data.Entity.SqlServer.<>c__DisplayClass1.<Execute>b__0() +10
System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Func`1 operation) +75
[EntityException: An exception has been raised that is likely due to a transient failure. If you are connecting to a SQL Azure database consider using SqlAzureExecutionStrategy.]
System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Func`1 operation) +184
System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation) +77
System.Data.Entity.Core.EntityClient.EntityConnection.Open() +253
[EntityException: The underlying provider failed on Open.]
System.Data.Entity.Core.EntityClient.EntityConnection.Open() +323
System.Data.Entity.Core.Objects.ObjectContext.EnsureConnection(Boolean shouldMonitorTransactions) +133
System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction(Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess) +46
System.Data.Entity.Core.Objects.<>c__DisplayClass7.<GetResults>b__5() +155
System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Func`1 operation) +75
[EntityException: An exception has been raised that is likely due to a transient failure. If you are connecting to a SQL Azure database consider using SqlAzureExecutionStrategy.]
System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Func`1 operation) +184
System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption) +281
System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0() +11
System.Data.Entity.Internal.LazyEnumerator`1.MoveNext() +45
System.Linq.Enumerable.FirstOrDefault(IEnumerable`1 source) +121
System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.<GetElementFunction>b__1(IEnumerable`1 sequence) +40
System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.ExecuteSingle(IEnumerable`1 query, Expression queryRoot) +60
System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute(Expression expression) +113
System.Data.Entity.Internal.Linq.DbQueryProvider.Execute(Expression expression) +99
System.Linq.Queryable.FirstOrDefault(IQueryable`1 source, Expression`1 predicate) +249
.Areas.Data.Controllers.ExportsController.Overview(String exportGuid) in C:\Own\Projects\\codebase\\Areas\Data\Controllers\ExportsController.cs:0
lambda_method(Closure , ControllerBase , Object[] ) +104
System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +14
System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +157
System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) +22
System.Web.Mvc.Async.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +32
System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +50
System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +228
System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +26
System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +100
System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +12
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9748493
System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +48
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +159

Answer 1

As the errors you shared stated this is happening due to transient errors. "[EntityException: An exception has been raised that is likely due to a transient failure.
Please add a retry logic to your applications.
public void HandleTransients()
{
var connStr = "some database";
var _policy = RetryPolicy.Create < SqlAzureTransientErrorDetectionStrategy(
retryCount: 3,
retryInterval: TimeSpan.FromSeconds(5));
using (var conn = new ReliableSqlConnection(connStr, _policy))
{
// Do SQL stuff here.
}
}
Learn more about it here and here.