Server Error in '/casestudies' Application.

'lstUoAs' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: 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.ArgumentOutOfRangeException: 'lstUoAs' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: 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:


[ArgumentOutOfRangeException: 'lstUoAs' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value]
   System.Web.UI.WebControls.ListControl.PerformDataBinding(IEnumerable dataSource) +2751496
   MyASPControls.GroupedDropdownList.PerformDataBinding(IEnumerable dataSource) +36
   System.Web.UI.WebControls.ListControl.OnDataBinding(EventArgs e) +303
   System.Web.UI.WebControls.ListControl.PerformSelect() +38
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +76
   WebRole1.Results.LoadUoAs() +2107
   WebRole1.Results.LoadFilters() +33
   WebRole1.Results.FilterResults(Int16 page) +1197
   WebRole1.Results.Page_Load(Object sender, EventArgs e) +2788
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +52
   System.Web.UI.Control.OnLoad(EventArgs e) +97
   System.Web.UI.<LoadRecursiveAsync>d__246.MoveNext() +229
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +102
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +64
   System.Web.Util.WithinCancellableCallbackTaskAwaiter.GetResult() +32
   System.Web.UI.<ProcessRequestMainAsync>d__523.MoveNext() +4853


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