Symptoms

SP 2013 K2 App - Throwing error "accessed denied" when opening forms
 

Diagnoses

I've installed the k2 App for SharePoint 2013
I've added the app to a test site collection
I created a custom list with a few fields
I configured K2 for the list with forms, workflow, and reports.
I created a workflow successfully and deployed it.
Now, when I try to add a new item, I am getting an error : 401 - Unauthorized: Access is denied due to invalid credentials. You do not have permission to view this directory or page using the credentials that you supplied.
 

Resolution

We reviewed the issue and identified there might be a configuration issue with the smart forms install, and after re-running the setup for smart forms, the form would load successfully on a new SharePoint site collection.