Error while Populating new webpart to SharePoint gallery

Question

I'm getting this error when I try to populate a webpart,

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() Troubleshoot issues with Windows SharePoint Services.

Note that, I populated other webparts before as well but now none of webpart is actually getting populated to the SharePoint webpart gallery.

I did read solution for wniforms, but will it be the issue as the webpart that used to populate before are not even populating now.

    <appSettings>
  <add key="aspnet:MaxHttpCollectionKeys" value="1001" />
</appSettings>

Answer 1

This is caused by a recent security update by Microsoft. By default the size of the Forms collection is now 1000 items.

You can find more about this and a workaround at this URL:

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