Absolutely stuck on Workflow 'Failed to start (retrying)'

Question

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.

Edit 1

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.

Answer 1

I had several similar issues while developing workflows on 2007 platform. If you are certain your code is good you can try folowing procedures:

• Change assembly version (from original 1.0.0.0 to something else) and then try to redeploy it. I believe it will run as new instance of same workflow
• Copy your workflow in another project (if possible) and then try to reuse it

This two approaches solved most of my problems back in 2007. I hope they will do some good for you on 2010.

SharePoint workflows are evil and after I received answer from Microsoft representative that in 2010 there are no major changes in workflow deployment and development (at least in areas I was interested in) I am constantly refusing to use them for my ongoing projects.