Symptoms

User is seeing message 'You have reached the daily limit for comments/replies posted by a user'

 Cause

User is not passing Table API ACL. 

Resolution

The behavior seen is due to the Table API ACL being activated. The ACL can be found at the following link: 

<Instance name>.service-now.com/nav_to.do?uri=sys_security_acl.do?sys_id=9ef8bc918733320025fbd1a936cb0bdd 

Since the user does not have proper roles to pass this ACL, they are unable to post a comment here. Please see our docs for further information on the API and adding security restrictions. This ACL is not active by default. The solution here is to either revert this ACL back to OOB, or add the proper roles to the user to allow them to pass the restriction.

Additional Information

REST API security 
https://docs.servicenow.com/bundle/london-application-development/page/integrate/inbound-rest/concept/rest-table-access.html