Opera browser causes Invalid viewstate error

We are receiving the following error whenever someone using the Opera browser uses our web forms:

BASE EXCEPTION: System.FormatException: Invalid length for a Base-64 char array.

at System.Convert.FromBase64String(String s)

at System.Web.UI.LosFormatter.Deserialize(String input)

at System.Web.UI.Page.LoadPageStateFromPersistenceMedium()

EXCEPTION: System.Web.HttpUnhandledException: Exception of type System.Web.HttpUnhandledException was thrown. --> System.Web.HttpException: Invalid_Viewstate

Client IP: 165.228.133.11

Port: 46730

User-Agent: Opera/9.0 (Windows NT 5.1; U; en)

We are currently running under Asp.Net v1.1

Is there some sort of setting that needs to be modified to prevent these types of errors?

Hi,

The View State data might has been truncated in Opera 9.0, the View State feature will experience a FormatException error in theFromBase64String method, and you receive the following error message:

Invalid length for a Base-64 char array

Please check how long is your View State data in IE browser and Opera. You can disable the View State of certain control by setting its EnableViewState property to false.