Server Error in '/' Application.

An item with the same key has already been added.

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.ArgumentException: An item with the same key has already been added.

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:


[ArgumentException: An item with the same key has already been added.]
   System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +56
   System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) +14287305
   WebPartGroupMenu.main.OnPreRender(EventArgs e) in C:\Programming\PinotrProject.Platform\WebParts\WebPartGroupMenu\main.ascx.cs:422
   System.Web.UI.Control.PreRenderRecursiveInternal() +107
   System.Web.UI.Control.PreRenderRecursiveInternal() +204
   System.Web.UI.Control.PreRenderRecursiveInternal() +204
   System.Web.UI.Control.PreRenderRecursiveInternal() +204
   System.Web.UI.Control.PreRenderRecursiveInternal() +204
   System.Web.UI.Control.PreRenderRecursiveInternal() +204
   System.Web.UI.Control.PreRenderRecursiveInternal() +204
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +7675


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.6.1055.0