I had to build a fairly complex workflow not long ago. The workflow was built in SharePoint Designer 2013 and had a lot of moving parts to it. So many, that when I went to publish it I received the following error message: “Microsoft.Workflow.Client.ActivityValidationException: Workflow XAML failed validation due to the following errors: Activity “SomeXActivity” has 65 arguments, which exceeds the maximum number of arguments per activity (50).” This error message is actually telling us that our workflow has too many variables within it. Basically, this is happening because when the workflow is running the Workflow Manager has to manage more 58 (in my case) variables. Workflow Manager only allows there to be 50 variables in the workflow… by default.