I had started building a custom VS2010 workflow, and I was able to test it, and everything worked fine. I then had to make some changes in my project (feature receiver, custom task edit form), and now upon starting my workflow, I constantly get nothing but
Failed on Start (retrying). The only error message in the logs is the following, which is followed by a call stack.
Engine RunWorkflow: System.Workflow.ComponentModel.Compiler.WorkflowValidationFailedException: The workflow failed validation.
I saw this post here, and tried adding the line to the csproj that the answer had, but that didn't provide a solution either. I've fully retracted, remove, disassociated, whathaveyou the workflow from SharePoint, thinking it could be a caching issue, but I'm absolutely stuck. I've gone thru each Task & code activity to verify correlation tokens and code behind methods match.
I have another workflow in a separate project, in the same solution which runs and completes without issue. So this issue is definitely specific to the current workflow.