Server Error in '/' Application.

The cast to value type 'System.Decimal' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.

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.

Exception Details: System.InvalidOperationException: The cast to value type 'System.Decimal' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.

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:


[InvalidOperationException: The cast to value type 'System.Decimal' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.]
   System.Data.Entity.Core.Common.Internal.Materialization.ErrorHandlingValueReader`1.GetValue(DbDataReader reader, Int32 ordinal) +117
   lambda_method(Closure , Shaper ) +105
   System.Data.Entity.Core.Common.Internal.Materialization.Coordinator`1.ReadNextElement(Shaper shaper) +207
   System.Data.Entity.Core.Common.Internal.Materialization.SimpleEnumerator.MoveNext() +78
   System.Data.Entity.Internal.LazyEnumerator`1.MoveNext() +100
   System.Linq.Enumerable.Single(IEnumerable`1 source) +119
   System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.<GetElementFunction>b__3(IEnumerable`1 sequence) +5
   System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.ExecuteSingle(IEnumerable`1 query, Expression queryRoot) +30
   System.Data.Entity.Core.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute(Expression expression) +64
   System.Data.Entity.Internal.Linq.DbQueryProvider.Execute(Expression expression) +90
   System.Linq.Queryable.Sum(IQueryable`1 source) +152
   WebApplication.TemplateKategorie.NactiDynamickyRemarketing() in C:\Projects WebForms\EvolutionGroupSK\WebApplication\TemplateKategorie.aspx.cs:405
   WebApplication.TemplateKategorie.Page_Load(Object sender, EventArgs e) in C:\Projects WebForms\EvolutionGroupSK\WebApplication\TemplateKategorie.aspx.cs:44
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +85
   System.Web.UI.Control.OnLoad(EventArgs e) +79
   System.Web.UI.Control.LoadRecursive() +130
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2848


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4682.0