SharePoint Designer Worflow: Could not deserialize object


I have an application using custom workflow activities ( Look up etc) tied with SharePoint Designer . The application site collection backup was replicated to Testing from Prod. Upon opening the workflow with designer kept on getting Could not deserialize object error .

Various factors can cause this error like Designer cache etc, for me the problem was that the workflow activites class was not registered in the web config of the application .

The line had to be added under 

<System.Workflow.ComponentModel.WorkflowCompiler> / <authorizedTypes>.

hoping it makes someones life easy

side note:

why the hell people used SPD in production ? I still can't get it




The reason folks used it was for the design interface, and setting up BCS connections. There are a few "gotcha" to know. I have one page that SPD deletes a ASPNET component every time I edit the page.