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This is error messages.


Server Error in '/trialwebsite' Application.

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.
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: 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.

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: 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.]
System.Web.UI.ClientScriptManager.ValidateEvent(String uniqueId, String argument) +367
System.Web.UI.Control.ValidateEvent(String uniqueID, String eventArgument) +83
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +51
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +31
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +32
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +72
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3837

Version Information: Microsoft .NET Framework Version:2.0.50727.42; ASP.NET Version:2.0.50727.42

Regards,
Pinakin

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Generated

This error means the server received a postback/callback value it did not recognize as having been emitted by the page when it was rendered. Common root causes are dynamically created controls or list items that are not reconstructed early enough in the page lifecycle, or client-side code that posts custom arguments the server never recorded.

Practical checklist (apply in this order):

  • Recreate any runtime controls on every request, using the same IDs and the same control order, and do it in Page_Init (so the controls exist before view state and event handling happen).
  • If a DropDownList/ListBox is filled dynamically, either rebind it early (Init/PreLoad) or persist the options so the server can validate posted values.
  • If client script calls postback with custom arguments, register those expected values on the server during rendering so event-validation will accept them.
  • For diagnosis, capture the POST body in the browser (look for EVENTTARGET and EVENTARGUMENT and any control values) and compare those posted values to the HTML rendered earlier and to server-side data sources.

Example patterns (C#):

protected void Page_Init(object sender, EventArgs e)
{
    // recreate dynamic controls here (same IDs)
}

protected override void Render(HtmlTextWriter writer)
{
    // register expected postback arguments before output
    foreach (ListItem li in myDropDown.Items)
        Page.ClientScript.RegisterForEventValidation(myDropDown.UniqueID, li.Value);

    base.Render(writer);
}

Notes and cautions: event validation is a security feature; disabling it (EnableEventValidation="false") only as a last resort is risky and requires additional server-side validation. For AJAX/UpdatePanel scenarios remember to register values or recreate controls on each partial render as well. This guidance addresses the typical situations implied by ’s stack trace and the follow-up from

Member Avatar for Ana D.

Hi pbbhatt,

I'm having the same error. How did you fix it? It would be great if you could explain your solution!

Thanks,

Ana

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