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

When the number of controls / fields in an Asp.Net 3.0 form exceeds 1000, the following error message will be thrown.

Operation is not valid due to the current state of the object.  
  at System.Web.HttpValueCollection.ThrowIfMaxHttpCollectionKeysExceeded()    
  at System.Web.HttpValueCollection.FillFromEncodedBytes(Byte[] bytes, Encoding encoding)    
  at System.Web.HttpRequest.FillInFormCollection()

This is because the Microsoft security update MS11-100 limits the maximum number of form keys, files, and JSON members to 1000 in an HTTP request.

When there is a HTTP request requesting for a page which has more than 1000 fields/controls, this exception in thrown.

The good thing is, that there is a fix for the issue, which can be made by altering the settings in the web.config file. Adding the following line to the <appSettings> section will increase the limit from 1000 to 2000, you can configure the <appSettings> section based on your needs.

<appSettings>

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

appSettings>

For more information please visit the following post in Microsoft’s support center.



http://support.microsoft.com/kb/2661403