Server Error in '/' Application.

The cast to value type 'Int32' 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 'Int32' 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 'Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.]
   System.Data.Common.Internal.Materialization.ErrorHandlingValueReader`1.GetValue(DbDataReader reader, Int32 ordinal) +165
   lambda_method(Closure , Shaper ) +1188
   System.Data.Common.Internal.Materialization.Coordinator`1.ReadNextElement(Shaper shaper) +366
   System.Data.Common.Internal.Materialization.SimpleEnumerator.MoveNext() +91
   System.Linq.Enumerable.FirstOrDefault(IEnumerable`1 source) +146
   TatilTurSitesi.TurDetay.Page_Load(Object sender, EventArgs e) in D:\Marenova\TatilTurSitesi\TatilTurSitesi\TurDetay.aspx.cs:55
   System.Web.UI.Control.OnLoad(EventArgs e) +106
   System.Web.UI.Control.LoadRecursive() +68
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3785


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.7.3640.0