Users gets Access Denied error when using K2 SmartForms as the New/Edit/Display forms

Issue

An Access Denied error is observed when a user interacts with items and documents using K2 SmartForms as the New, Edit and Display forms for the SharePoint list/library. There are no issues when using the standard SharePoint forms. 

Error Code

Sorry, you don't have access. 

Resolution

This is expected if you break permissions inheritance from the parent and assigned permissions directly on the SharePoint list/library rather than at the site level.

The New, Edit and Display forms (NewForm.aspx, EditForm.aspx, DispForm.aspx) are saved in the hidden K2Pages library. Navigate to https://<SITEURL>/K2pages and grant the user at least Read permissions to this library. 

Related Links

https://help.nintex.com/en-US/k2five/userguide/5.5/default.htm#Create/K2ForSharePoint/Create/CreateForms.htm