We were receiving the above error on running a custom aspx page.
This page was configured to be called on click of an ISV.config button from an entity’s form.
The page was using CrmService web service to update the entity on which it was being called.
On checking the stack trace, we found that error was coming from within this function of the page
CrmService crmService = new CrmService(); crmService.Url = //web service url crmService.Credentials = System.Net.CredentialCache.DefaultCredentials; salesorder salesOrder = new salesorder(); salesOrder.new_issuer = userName; salesOrder.salesorderid = new Key(); salesOrder.salesorderid.Value = new Guid(poID); crmService.Update(salesOrder);