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Page.EnableEventValidation Property

Updated: May 2010

Gets or sets a value indicating whether the page validates postback and callback events.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

public virtual bool EnableEventValidation { get; set; }
<asp:Page EnableEventValidation="True|False" />

Property Value

Type: System.Boolean
true if the page validates postback and callback events; otherwise, false. The default is true.


The EnableEventValidation property was set after the page was initialized.

When the EnableEventValidation property is set to true, ASP.NET validates that a control event originated from the user interface that was rendered by that control. A control registers its events during rendering and then validates the events during postback or callback handling. For example, if a list control includes options numbered 1, 2, or 3 when the page is rendered, and if a postback request is received specifying option number 4, ASP.NET raises an exception. All event-driven controls in ASP.NET use this feature by default.

If you write client script that changes a control in the client at run time, you might have to use the RegisterForEventValidation method in order to avoid false event validation errors.

Security noteSecurity Note:

This feature reduces the risk of unauthorized or malicious postback requests and callbacks. It is strongly recommended that you do not disable event validation.

You set the EnableEventValidation property by setting the enableEventValidation attribute of the @ Page directive or the enableEventValidation attribute of the pages element in the Web.config file. If you set this property in code, you must set it before the page is initialized.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0




May 2010

Improved explanation of the function of the property.

Customer feedback.

October 2009

Corrected text that indicated the property could be set in code.

Content bug fix.