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 84:                         aanraders = aanraders.Union(templijst).Distinct.ToList
Line 85: 
Line 86:                         litTitle.Text = db.tblRichtingCategorie.Where(Function(c) c.categorieID = catID).First.naam '& " -> " & db.tblRichting.Where(Function(c) c.richtingID = onderwijsstructuur).First.naam
Line 87:                         litWerkgroep.Text = db.tblRichtingCategorie.Where(Function(c) c.categorieID = catID).First.naam & " / " & db.tblRichting.Where(Function(c) c.richtingID = onderwijsstructuur).First.naam
Line 88:                     Else

Source File: D:\inetpub\wwwroot\cnosite\components\cno_opleidingen\cno_opleidingen.ascx.vb    Line: 86

Stack Trace:


[InvalidOperationException: Sequence contains no elements]
   System.Linq.Enumerable.First(IEnumerable`1 source) +417
   components_cno_filters_cno_opleidingen.filterNascholingen() in D:\inetpub\wwwroot\cnosite\components\cno_opleidingen\cno_opleidingen.ascx.vb:86
   components_cno_filters_cno_opleidingen.Page_Load(Object sender, EventArgs e) in D:\inetpub\wwwroot\cnosite\components\cno_opleidingen\cno_opleidingen.ascx.vb:13
   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