Some plug-ins or custom workflow activities in your system appear to be using the Microsoft CRM 4.0 SDK. Use of the Microsoft ...

Some plug-ins or custom workflow activities in your system appear to be using the Microsoft CRM 4.0 SDK. Use of the Microsoft CRM 4.0 SDK is not supported in this release. For information about how to upgrade custom code, refer to the Microsoft Dynamics CRM 2011 SDK topic "Upgrade Your Code from Microsoft Dynamics CRM 4.0 to Microsoft Dynamics CRM".