To fix “Workflow failed on start (retrying)” error we did the following:
1. From the local machine/development machine, the Visual Studio solution property for “Assembly Deployment Target” is set as “GlobalAssemblyCache” shown below:
2. Double click the package file in the solution
3. Click "Advanced" tab near the bottom of the page
4. Click "Add" >> "Add Existing Assembly" from "Add" button near top of screen
5. Click ellipses button next to Source Path
6. Navigate to where you project's bin\Debug folder is located
7. Select the .dll file which holds the name of your project
8. From the "Add Existing Assembly" modal window, select "WebApplication" option
9. Click "Ok" and "Deploy"
10. Navigate to the bin/Debug folder for the Visual Studio project, and the .wsp file is what needs to be pushed to the SharePoint Server
