Home / Community & Support / Developer Productivity Tools Forums / ASP.NET > Ajax > Invalid postback/callback argument

• Slayde Barnes Master

  Posted on May 14, 2007 (permalink)

  Hi. The page found here throws the following error intermittently. It uses r.a.d. Ajax. Help! Thanks.
  
  

  System.ArgumentException: Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
  
  Additional details of the error are,
  

  System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.ArgumentException: Invalid postback or callback argument.  Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page.  For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them.  If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
     at System.Web.UI.ClientScriptManager.ValidateEvent(String uniqueId, String argument)
     at System.Web.UI.Control.ValidateEvent(String uniqueID, String eventArgument)
     at System.Web.UI.WebControls.DropDownList.LoadPostData(String postDataKey, NameValueCollection postCollection)
     at System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection)
     at System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad)
     at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
     --- End of inner exception stack trace ---
     at System.Web.UI.Page.HandleError(Exception e)
     at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
     at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
     at System.Web.UI.Page.ProcessRequest()
     at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context)
     at System.Web.UI.Page.ProcessRequest(HttpContext context)
     at ASP.default_aspx.ProcessRequest(HttpContext context)
     at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
     at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
  		

• Jason Maronge Master

  Posted on May 14, 2007 (permalink)

  Alex,
  
  Sometimes ASP.NET throws this exception on fast clicks/post-backs. Is this the case at your end?
  Try adding the enableEventValidation property to the Pages element in the web config and setting it to false.
  

  <pages enableEventValidation="false" >
  
  Jason

• Jatin

  Posted on Oct 11, 2007 (permalink)

  i think by this security of the application going to week. what do you think please reply, thanks in advance.
  

• Alex

  Posted on Oct 11, 2007 (permalink)

  It's not a safe thing to turn off event validation. This article from Microsoft details what it does and why you shouldn't turn it off,
  

  The event validation mechanism reduces the risk of unauthorized postback requests and callbacks. When the EnableEventValidation property is set to true, ASP.NET allows only the specific events that can be raised on the control during a postback request or callback. In this model, a control registers its events during rendering and then validates the events during postback or callback handling. All event-driven controls in ASP.NET now use this feature by default.

  It is strongly recommended that you do not disable event validation. Before disabling event validation, you should be sure that no postback could be constructed that would have an unintended effect on your application.

  The full article can be found here: http://msdn2.microsoft.com/en-us/library/system.web.ui.page.enableeventvalidation.aspx
  
  I haven't used the latest AJAX Manager from Telerik yet. That might have resolved this issue.
  

• Alaa Majzoub

  Posted on Feb 17, 2008 (permalink)

  Telerik ajax manager didn't work
  
  

• Nicolaï Intermediate

  Posted on Jun 27, 2008 (permalink)

  Had a similar error msg while debugging.
  Turns out it was caused by some code in the page load, that was outside the "If not ispostback". So check that, among other things...
  

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