I ran into this issue with a client project.
The Visual Studio workflow contains a Delay activity. The first time the workflow was deployed to the environment, everything worked fine. The delay activity resumed the workflow at the appropriate time. We proceeded with UAT and made a few changes to the process and redeployed an update to the workflow. The delay activity would never resume after the update!
What I suspect was happening is documented in the Microsoft KB article cause #5.
I was able to recreate the problem in my environment and to resolve the issue I followed the following steps.
- Deactivated the workflow feature which removes the workflow from the site.
- Retracted the solution from SharePoint
- Gave the assembly a new version #. (Updated all of my references)
- Added and Deployed the updated solution to SharePoint
- Reactivated the workflow features and reattached them to the list
The workflow worked fine after completing this process!