asp.net error: Operation is not valid due to the current state of the object
ASP.NET requests that have lots of form keys, files, or JSON payload receive an error response from the server. The Application log on the server has a Warning entry with a Source that is a specific version of ASP.NET, and an Event ID of 1309. The event log contains one of the following messages:
Message 1:
Application information:
Application domain: /LM/W3SVC/1/ROOT/<App Domain>
Trust level: Medium
Application Virtual Path: <VDIR Path>
Application Path: <App Path>
Machine name: <Machine Name>
Process information:
Process ID: 0001
Process name: w3wp.exe
Account name: IIS APPPOOL\DefaultAppPool
Exception information:
Exception type: HttpException
Exception message: The URL-encoded form data is not valid.
at System.Web.HttpRequest.FillInFormCollection()
at System.Web.HttpRequest.get_Form()
at System.Web.HttpRequest.get_HasForm()
at System.Web.UI.Page.GetCollectionBasedOnMethod(Boolean dontReturnNull)
at System.Web.UI.Page.DeterminePostBackMode()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
Message 2:
Application information:
Application domain: /LM/W3SVC/1/ROOT/<App Domain>
Trust level: Medium
Application Virtual Path: <VDIR Path>
Application Path: <App Path>
Machine name: <Machine Name>
Process information:
Process ID: 0001
Process name: w3wp.exe
Account name: IIS APPPOOL\DefaultAppPool
Exception information:
Exception type: InvalidOperationException
Exception message: Operation is not valid due to the current state of the object.
at System.Web.HttpRequest.FillInFilesCollection()
at System.Web.HttpRequest.get_Files()
at FileUpload.Page_Load(Object sender, EventArgs e)
at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)
at System.Web.UI.Control.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint
to resolve this problem, you should change your web.config
<configuration>
<appSettings>
<add key="aspnet:MaxHttpCollectionKeys" value="5000" />
</appSettings>
</configuration>