Applies to: CopyMove for SharePoint 2007
Problem
This error shows when accessing any of the CopyMove pages.
Cause
An unknown error can of course be anything. But this is also just the general error message that SharePoint shows in a production environment in order to not compromise any system information to end users.
Resolution
This error usually occurs because of a missing resource file - see this faq to resolve this problem.
To see the exact error message, open the web.config file of the SharePoint Web application and set the CallStack attribute to true on the SafeMode element, and the mode attribute to Off on the customErrors element. Then repeat your actions to reproduce the error.