I ran into an interesting issue today upgrading a custom workflow activity. I received this error:
<OrganizationServiceFault xmlns="http://schemas.microsoft.com/xrm/2011/Contracts" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
<ErrorCode>-2147200995</ErrorCode>
<ErrorDetails xmlns:a="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />
<Message>Duplicate workflow activity group name: ", activity name: 'Assign email regarding to case'.</Message>
<Timestamp>2013-06-14T19:45:24.1533902Z</Timestamp>
<InnerFault>
<ErrorCode>-2147200995</ErrorCode>
<ErrorDetails xmlns:a="http://schemas.datacontract.org/2004/07/System.Collections.Generic" />
<Message>Duplicate workflow activity group name: ", activity name: 'Assign email regarding to case'.</Message>
<Timestamp>2013-06-14T19:45:24.1533902Z</Timestamp>
<InnerFault i:nil="true" />
<TraceText i:nil="true" />
</InnerFault>
<TraceText i:nil="true" />
</OrganizationServiceFault>
It turns out that the Plugin Registration tool didn't like the fact that I did not have a WorkflowActivityGroupName specified, as you can see here:
I added one and the error went away.