Accessing forms displays an error for end users:
"Access denied. You do not have permission to perform this action or access this resource"
In this scenario the error occurs when accessing K2 Forms or the Artifact Page on a sub-site where the permission inheritance is broken with the root site. The issue only occurs for users that has no access to the root site.
K2 Designers, even with the needed Sharepoint Group memberships to Design might also see Access Denied errors:
End users will get an access denied error when trying to use K2 forms like the New, Edit and Display forms.
Designers will not be able to get into the Artifact page.
This is expected where sub-sites have inheritance broken and users have no access to the root site.
Using K2 artifacts on sub-sites may require Read rights on the root site of the site collection if permission inheritance is broken.
Please see the following documentation on all the rights (Links provided in the SEE ALSO Section):
Permissions required to use applications created with the K2 Cloud App.
Fix: Grant read rights to the users on the Root site.