When trying to debug a workflow created in SharePoint 2013 App using Visual Studio 2012 version, i am getting the error "workflow debugging prerequisites failed to complete". I tried to publish the app first and then debug, but still got the same error.
Is your Visual Studio fully updated?
The following link is for 2013 version but it seems to have encountered exactly the same error:
Have a look at the following link as well: http://blogs.msdn.com/b/officeapps/archive/2013/10/30/debugging-sharepoint-2013-workflows-using-visual-studio-2013.aspx
You must enable Service Bus debugging if you want to debug workflows on Office 365. If your project targets SharePoint installed on your local network, you do not need to enable Service Bus debugging. Instead, you need to open incoming connections to TCP port 12292. If you use Windows Firewall with Advanced Security, you can simply enable the rule “Workflow Manager Tools 1.0 for Visual Studio 2012 - Test Service Host”. If you try to debug against a SharePoint host on the local network without opening the port, Visual Studio will prompt you to enable the rule.
The problem was with workflow manager configuration. Reconfiguring it again resolved the issue. Also, since the SharePoint version was updated from RTM to March 2013 Public Update, i had to register the workflow service again. Reference http://www.andrewconnell.com/blog/Updates-For-SP2013-Workflow