This post comes from, Will Phifer.
He was working on some workflows, and had installed Nintex to test out its functionality. Had had removed Nintex from the environment, but some of the workflows in the environment were then getting errors.
As it turned out, it only happened with workflows created in SharePoint Designer. All of the OOTB workflows were working just fine.
In the environment, he couldn't create new workflows and for existing ones they would fail.
The error message was appearing after clicking finish. ‘Check Workflow’ was reporting no errors.
For some reason, when he removed Nintex it didn’t completely remove. Notice this line in the web.config which still made reference to the removed Nintex product.
Removing this line from the web.config file resolved the issue. Good thing is that they all set to a retrying state which actually completes once the correction has been made.