How can I use the WorkflowApplication in combination with a Custom Activity? I have a workflow containing a custom activity that sends an email. Of course, when I try to run it. It results in an error stating that it can't find the custom activity.
It is probably that the required assembly is missing. You can add the assembly reference to preload the assembly or using the assembly resolver. For more information, you can refer to the following thread:
How to solve unknow type problem when load a Xmal file