When trying to retract the NintexWorkflowCore2013.wsp solution from Central Administration, the following error might occur:
Core Retraction: XXXX-XXX-XXXX : Access to the path 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\BIN\NintexWorkflow\Nintex.Workflow.Live.QueueService.exe' is denied.
- Verify that Nintex.Workflow.Live.QueueService.exe exists at the referenced path.
- Stop the Nintex Live Workflow Queue Service across the farm.
- Retract the solution again.
- You can then re-deploy the solution to the desired web-applications, or remove the solution entirely.