There are situations for end users when they access their respective approval record (sysapproval_approver) in UI16 platform or Service Portal, they get the following alert pop-up specifying:
There must be a reference field on the form to associate approval with and item. Use Personalize Form Layout and select the Approving field
- Notice the "Approving" field of the approval record which is called as "document_id" at dictionary level shows the reference to the respective RITM, change request, etc. record.
- This field shows reference to the target table record. If the end user doesn't have read access to the target record - they will be presented with the mentioned message.
It logically makes sense since you're trying to request approval from that end user who "should" have at least read access to the target record such that approval/denial can happen on that referenced record successfully.
Additional Information / Solution
This can be controlled via Security Access Control Lists (ACLs) where you can grant at least read access to the target record. Please refer our product documentation for more details on access control.