Lỗi xảy ra ở Module: Banner, View: AdvertingHome, Section: ContentRight

System.NullReferenceException: Object reference not set to an instance of an object. at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry) at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry) at System.Data.SqlClient.SqlConnection.Open() at System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure) at System.Data.EntityClient.EntityConnection.Open() at System.Data.Objects.ObjectContext.EnsureConnection() at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption) at System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable.GetEnumerator() at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source) at Banner.Models.GalleryDL.GetAdvertisingItemByID(Int32 id, String lang) in D:\SETUPS\Ha Long\halong\Code\CTS.Web\Areas\Banner\Models\GalleryDL.cs:line 26 at Banner.Models.GalleryBL.GetAdvertisingItemByID(Int32 id, String lang) in D:\SETUPS\Ha Long\halong\Code\CTS.Web\Areas\Banner\Models\GalleryBL.cs:line 19 at Banner.Controllers.BannerController.AdvertingHome() in D:\SETUPS\Ha Long\halong\Code\CTS.Web\Areas\Banner\Controllers\BannerController.cs:line 39 at lambda_method(Closure , ControllerBase , Object[] ) at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass42.b__41() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass37.<>c__DisplayClass39.b__33() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.b__49() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.b__49() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.<>c__DisplayClass2a.b__20() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.b__22(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) at System.Web.Mvc.Controller.<>c__DisplayClass1d.b__18(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) at System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.b__3(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar) at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.<>c__DisplayClass4.b__3() at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.Wrap[TResult](Func`1 func) at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride)