Outdated Version of Workflow Runs After Publishing
After publishing a new version of a workflow, an outdated version still runs.
Go to List Settings > Workflow Settings.
Click on Remove a Workflow.
From list of the workflows and previous versions, ensure that the old versions are set to “No New Instances” and the most current is set to “Allow”.
This process should automatically happen when a workflow is published. If prompted for credentials during publishing, the web application pool might have recycled and the publish might not have completed correctly.
Also, if the workflow is very large, the SharePoint validation routine might be unable to process the workflow. There is an option in the “Startup Options” in the workflow designer to “Publish without validation”. Checking this option will skip the validation step and publish the workflow properly.