Upgrade Workflow Designer by uninstalling and reinstalling the product on each client machine.
Workflow Designer support history SDL Tridion 2013 SP1 Workflow Designer has a number of changed third-party software prerequisites compared to SDL Tridion 2009 SP1, SDL Tridion 2011 SP1, SDL Tridion 2011 SP1 HR1, SDL Tridion 2011 SP1 HR2 or SDL Tridion 2013.
Upgrading Workflow Designer client If you have upgraded your Content Manager databases and Content Manager server, and if you are logged on to the client machine as an administrator user, uninstall your existing client, then install the new one.
Upgrading existing default Workflow Process Definitions If you are upgrading from a release earlier than SDL Tridion 2011, you must update any existing Page Process and Component Process that are in use. This is because SDL Tridion 2011 changed these items.