Server Error in '/' Application.

Failed to load viewstate.  The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.

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: Failed to load viewstate.  The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.

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): Failed to load viewstate.  The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request.  For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.]
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +526
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +186
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +350
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +186
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +350
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +186
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +350
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +186
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +350
   System.Web.UI.Control.LoadChildViewStateByIndex(ArrayList childState) +186
   System.Web.UI.Control.LoadViewStateRecursive(Object savedState) +350
   System.Web.UI.Page.LoadAllState() +530
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2504