This error could occur after a Windows Update that reduces the allowable size of the HTTP Context to be sent/received from the server to the clients browser.
See the Vulnerability in ASP.NET Could Allow Denial of Service Microsoft Security Advisory for more information.
The default value of MaxHttpCollectionKeys
is set to 1000
by the security patch. You can override this value by adding the following key to the appsetttings
section in your web form’s web.config
file:
<add key="aspnet:MaxHttpCollectionKeys" value="10000" />
(10000
is just a suggestion; you can set it to the value of your liking.)