Operation is not valid due to the current state of the object.

Issue:

System.InvalidOperationExceptionOperation is not valid due to the current state of the object.

System.InvalidOperationException: Operation is not valid due to the current state of the object.
   at System.Web.HttpRequest.FillInFormCollection()
   at System.Web.HttpRequest.get_Form()
   at Rhino.Commons.LongConversationManager.LoadConversationFromRequest(Boolean& privateConversation)
   at Rhino.Commons.LongConversationManager.LoadConversation()
   at Rhino.Commons.HttpModules.UnitOfWorkApplication.UnitOfWorkApplication_BeginRequest(Object sender, EventArgs e)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
		
Cause:

Microsoft recently (12-29-2011) released an update to address several serious security vulnerabilities in the .NET Framework. MS11-100 was introduced just recently that handles potential DoS attacks.

Unfortunately the fix has also broken page POSTs with very large amounts of posted data (form fields). MS11-100 places a limit of 500 on postback items. The new default max introduced by the recent security update is 1000.

Adding the setting key to the web-config file overcomes this limitation, as in this example increases it to 2000.

<appSettings>
    <add key="aspnet:MaxHttpCollectionKeys" value="2000" />
 </appSettings>

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