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

i have a problem. uploader has been working fine for a long time, all of a sudden it won't upload more than 45 photos. MaxFileCount="60", if i upload 45 it works fine, regardless of file size, if i upload 46 it bombs and gives the following(using ShowDebugWindow=true):

Server Error in '/' Application.
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Operation is not valid due to the current state of the object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: Operation is not valid due to the current state of the object.

Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[InvalidOperationException: Operation is not valid due to the current state of the object.]
System.Web.HttpRequest.FillInFormCollection() +11091695
System.Web.HttpRequest.get_Form() +119
System.Web.HttpRequest.get_HasForm() +11085399
System.Web.UI.Page.GetCollectionBasedOnMethod(Boolean dontReturnNull) +124
System.Web.UI.Page.DeterminePostBackMode() +83
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +270

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Version Information: Microsoft .NET Framework Version:2.0.50727.3625; ASP.NET Version:2.0.50727.3634

anybody got any ideas? we have had the uploader in production on these two servers for almost a year and not had any problems, just randomly crept up on us??

thanks,
matt

<add key="aspnet:MaxHttpCollectionKeys" value="2001" />


added this key to the <appsettings> and it fixed the problem.

http://stackoverflow.com...mum-number-of-posted-for