Design view broken when create new WCF Workflow in Visual Studio 2013

Question

I open my visual studio 2013, create new WCF Workflow Service project. After creating files, vs open Service1.xamlx by default in design view, and I got this error:

    System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.VisualStudio.SharePoint.WorkflowExtensions, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
    File name: 'Microsoft.VisualStudio.SharePoint.WorkflowExtensions, Version=12.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

I try to install WorkflowManager offline but no luck. Please help me make it works.

Update1: I try to re-install my visual studio 2013, I get this warning:

Workflow Manager Tools 1.0 for Visual Studio.  
A certificate chain processed, but terminated in a root certificate which is not trusted by the trust provider.

I think maybe it's a reason, but still don't know how to fix.

Answer 1

The problem was gone after I re-install my Visual Studio 2013 without internet restriction. Maybe when restriction internet, VS cannot download some necessary packaging (ex: Workflow Manager Tools,...).