Server Error in '/' Application.

The control collection cannot be modified during DataBind, Init, Load, PreRender or Unload phases.

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.Web.HttpException: The control collection cannot be modified during DataBind, Init, Load, PreRender or Unload phases.

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:


[HttpException (0x80004005): The control collection cannot be modified during DataBind, Init, Load, PreRender or Unload phases.]
   System.Web.UI.ControlCollection.RemoveAt(Int32 index) +11657418
   System.Web.UI.ControlCollection.Remove(Control value) +40
   System.Web.UI.Control.AddedControl(Control control, Int32 index) +11727425
   Telerik.Web.UI.ControlItemCollection.OnInsertComplete(Int32 index, Object value) +64
   System.Web.UI.StateManagedCollection.InsertInternal(Int32 index, Object o) +318
   System.Web.UI.StateManagedCollection.System.Collections.IList.Add(Object value) +45
   Telerik.Web.UI.RadPanelItemCollection.AddRange(RadPanelItem[] items) +52
   WebStore.MasterPage.BindCategoryPanelBar(MasterDataKey selectedCat) +163
   WebStore.MasterPage.Page_Load(Object sender, EventArgs e) +543
   System.Web.UI.Control.OnLoad(EventArgs e) +108
   System.Web.UI.Control.LoadRecursive() +90
   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:4.8.4700.0