Mahmoud works through Document Attachment Error with GP 2015 R2 – “A Save Operation on table ‘coAttachMSTR’ has created a duplicate key error”
Dynamics GP Essentials: Document Attachment Error with GP 2015 R2 – “A Save Operation on table ‘coAttachMSTR’ has created a duplicate key error”
Install, Upgrade & AdminSQL & DataGP 2015
Archived post from 2015. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.