Skip to Different Action Set
I have been working with different workflow tools. While one of the best feature which I found in another workflow tool is that, an administrator can re-run the error workflow instance at a particular action set.
For more details consider a workflow as mentioned below:
Start
then Step 1
then Step 2
then step 3 approval process
Step 5 if approved in step 3
Step 6 if rejected in step 3.
This is a simple workflow. Now user has run the workflow and the approval task is assigned to a approver. Approver performs the task. Onec the approver performs the action. For some reason the workflow got errored out and no outcome is updated in the list.
In this scenario, currently the option is to terminate the workflow and reinstantiate. However, this is not feasible as users will be annoyed performing same task again and again.
Hence in this scenario the admin people should have the flexibility to re-run the instance either from step 3/4 depending upon the action performed by approver.
This option is available in another workflow tool. Hope Nintex includes this feature as well. This will be very helpful for production support and hence reduce the burden of users redoing the approver process for errored workflow.

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Veronika commented
I had the same requirement since years, but as a workaround I like to use following approach by Vadim Tabakman to restart a workflow in the middle when failed. I think it will be helpful for you as well: http://www.vadimtabakman.com/nintex-workflow-smart-restart-workflow-middle-of-a-workflow.aspx