Symptoms

We have deployed K2 app on SharePoint 2013 and added the app and while registering below error thrown

10702 Retrying the SharePointIntegration Service Instance as the K2 Service Account did not resolve the issue. Error occurred trying to Execute (K2 Application) - executeManageK2ApplicationForms
Exception Details:
Object reference not set to an instance of an object.
 

Diagnoses

The issue was caused by the fact that this specific site collection is configured to not allow standard OOB SharePoint document library to be created. When using SharePoint UI (Add an App page), user can not add the OOB SharePoint document library or list as well.
 

Resolution

The issue was resolved by creating the "K2Pages" document library manually using the same content from the working site collection.