Summary:What happens to running workflows when you retract the nintexworkflow2010.wsp or nintexworkflow2013.wsp solution for the web application?
Product:All Workflow Products
If your Farm is on a release after January 2015 (2010 = Version 220.127.116.11+ / 2013 Version 18.104.22.168+) you will have nintexworkflow2010core.wsp or nintexworkflow2013core.wsp globally deployed or the option to deploy it.
The "Core" solution covers running workflows for farm members with the Timer service running and no web application running.
This has the added benefit of allowing you to retract the Primary solution and still have running workflows being uninterrupted.
What effect does it have on the user's running workflows? Tasks or related views of tasks will get popup with an error. This is because we have removed the binaries need to compile these view and response forms.
When you redeploy the solution nintexworkflow2010/2013.wsp it will restore interaction with these objects again. IIS Reset is not mandatory but recommended.