I think I found the answer here: *Thank you for your feedback! The .NET 3.5 Workflow project type is no longer supported in VS2017. This is by design as WF from .NET 3.5 (System.Workflow) has been deprecated since 2012. While you will not be able to create new projects, it is still possible to open old projects if you install Office Developer Tools. But only SharePoint 2010 workflows are still supported.*
I forgot that there was some huge WWF update years ago and all the plumbing and libraries changed. The project I'm trying to open is the old style that references System.Workflow. As a test I created a new stub WWF project and I see it references System.Activities. So it looks like the project which opened in VS2015 two weeks ago is no longer supported by VS2017 ... another subtle trap for the complacent or trusting. The comment above hints that I *might* be able to open it if certain conditions are met, but I'm not confident of the outcome and waste of time. *GK* On 22 August 2017 at 08:51, Greg Keogh <gfke...@gmail.com> wrote: > After upgrading to Visual Studio 2017 I can't open any Windows Workflow > projects (Incompatible, The application is not installed). > > Various advice from searches suggests to check WWF in the Individual > Components list (seems obvious), but it weirdly makes no difference. Others > suggest you need SharePoint support, others suggest Framework 3.5 is > needed. It all makes no difference. > > There must be some other dependent piece of dark matter that I can't find. > Any ideas anyone? > > *Greg K* >
