Server Error in '/' Application.

Sequence contains no elements

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: Sequence contains no elements

Source Error:


Line 278:                        aanraders = aanraders.Union(templijst).Distinct.ToList
Line 279:
Line 280:                        litTitle.Text = db.tblRichtingCategorie.Where(Function(c) c.categorieID = catID).First.naam '& " -> " & db.tblRichting.Where(Function(c) c.richtingID = onderwijsstructuur).First.naam
Line 281:                        litWerkgroep.Text = db.tblRichtingCategorie.Where(Function(c) c.categorieID = catID).First.naam & " / " & db.tblRichting.Where(Function(c) c.richtingID = onderwijsstructuur).First.naam
Line 282:                    Else

Source File: D:\inetpub\wwwroot\cnosite\components\cno_opleidingen\cno_opleidingen.ascx.vb    Line: 280

Stack Trace:


[InvalidOperationException: Sequence contains no elements]
   System.Linq.Enumerable.First(IEnumerable`1 source) +417
   components_cno_filters_cno_opleidingen.filterInterne() in D:\inetpub\wwwroot\cnosite\components\cno_opleidingen\cno_opleidingen.ascx.vb:280
   components_cno_filters_cno_opleidingen.Page_Load(Object sender, EventArgs e) in D:\inetpub\wwwroot\cnosite\components\cno_opleidingen\cno_opleidingen.ascx.vb:11
   System.Web.UI.Control.OnLoad(EventArgs e) +108
   System.Web.UI.Control.LoadRecursive() +90
   System.Web.UI.Control.LoadRecursive() +185
   System.Web.UI.Control.LoadRecursive() +185
   System.Web.UI.Control.LoadRecursive() +185
   System.Web.UI.Control.LoadRecursive() +185
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1533


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4494.0