Server Error in '/' Application.

Nullable object must have a value.

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: Nullable object must have a value.

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: Nullable object must have a value.]
   System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource) +56
   GovernanceUniversity.Models.OpeidingsSoortModel.get_EerstvolgendBasisOpleiding() in C:\SandboxOnline\Coachview\GovernanceUniversity\Models\OpleidingModel.cs:257
   ASP._Views_Course_Details_cshtml.Execute() in C:\SandboxOnline\Coachview\GovernanceUniversity\Views\Course\Details.cshtml:80
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197
   System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +105
   System.Web.WebPages.StartPage.RunPage() +17
   System.Web.WebPages.StartPage.ExecutePageHierarchy() +73
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +78
   RazorGenerator.Mvc.PrecompiledMvcView.Render(ViewContext viewContext, TextWriter writer) +273
   System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +291
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +56
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +52
   System.Web.Mvc.Async.<>c__DisplayClass3_6.<BeginInvokeAction>b__4() +198
   System.Web.Mvc.Async.<>c__DisplayClass3_1.<BeginInvokeAction>b__1(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.<>c.<BeginExecuteCore>b__152_1(IAsyncResult asyncResult, ExecuteCoreState innerState) +11
   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) +45
   System.Web.Mvc.<>c.<BeginExecute>b__151_2(IAsyncResult asyncResult, Controller controller) +13
   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.<>c.<BeginProcessRequest>b__20_1(IAsyncResult asyncResult, ProcessRequestState innerState) +28
   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() +577
   System.Web.<>c__DisplayClass285_0.<ExecuteStepImpl>b__0() +24
   System.Web.StepInvoker.Invoke(Action executionStep) +100
   System.Web.<>c__DisplayClass4_0.<Invoke>b__0() +17
   Microsoft.AspNet.TelemetryCorrelation.TelemetryCorrelationHttpModule.OnExecuteRequestStep(HttpContextBase context, Action step) +64
   System.Web.<>c__DisplayClass284_0.<OnExecuteRequestStep>b__0(Action nextStepAction) +54
   System.Web.StepInvoker.Invoke(Action executionStep) +84
   System.Web.<>c__DisplayClass4_0.<Invoke>b__0() +17
   Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule.OnExecuteRequestStep(HttpContextBase context, Action step) in /_/WEB/Src/Web/Web/ApplicationInsightsHttpModule.cs:164
   System.Web.<>c__DisplayClass284_0.<OnExecuteRequestStep>b__0(Action nextStepAction) +54
   System.Web.StepInvoker.Invoke(Action executionStep) +84
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +100
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +163


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4690.0