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ViewStateException Class

Represents the exception that is thrown when the view state cannot be loaded or validated. This class cannot be inherited.

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

<SerializableAttribute> _
<AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class ViewStateException _
	Inherits Exception _
	Implements ISerializable
Dim instance As ViewStateException

If an exception occurs when the page loads the view-state information, the page creates a ViewStateException object and passes it as an inner exception within an HttpException exception. The HttpException exception is re-thrown to be handled by the application.

The ViewStateException class stores information about the exception in the Message property. If the request has permission to access the ServerVariables property, then the Message property contains the values returned from the RemoteAddress, RemotePort, UserAgent, PersistedState, Referer, and Path properties; otherwise, the Message property contains a generic view-state error message.

A view-state exception can be the result of a Message Authentication Codes (MAC) validation error. If the page attribute enableViewStateMac is set to true, view-state information is encoded with a MAC identifier. When the view-state information is posted back to the server, the page verifies the encoding to ensure that it has not been altered by the user. If the page cannot validate the MAC encoding on the view-state information, it will throw an HttpException exception with the ViewStateException object as an inner exception.

For MAC validation to succeed, the view-state information must be hashed by the same key when it is sent and received. Within a Web farm, the machine key on each server should be set to a common key.

The following code example demonstrates how to implement a method that deserializes a base64-encoded string and returns an ICollection collection of property settings. The Deserialize method can throw an HttpException exception that contains a ViewStateException object as an inner exception. The example shows how you can catch an HttpException exception and retrieve the properties from the ViewStateException object.

Private Function LoadControlProperties(ByVal serializedProperties As String) As ICollection

    Dim controlProperties As ICollection = Nothing 

    ' Create an ObjectStateFormatter to deserialize the properties. 
    Dim formatter As New ObjectStateFormatter()

        ' Call the Deserialize method.
        controlProperties = CType(formatter.Deserialize(serializedProperties), ArrayList)
    Catch e As HttpException
        Dim vse As ViewStateException
        Dim logMessage As String

        vse = e.InnerException

        logMessage = "ViewStateException. Path: " + vse.Path + Environment.NewLine
        logMessage += "PersistedState: " + vse.PersistedState + Environment.NewLine
        logMessage += "Referer: " + vse.Referer + Environment.NewLine
        logMessage += "UserAgent: " + vse.UserAgent + Environment.NewLine


        If (vse.IsConnected) Then
            Throw e
        End If 
    End Try 
    Return controlProperties
End Function 'LoadControlProperties   


Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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