This Error Message Article explains the BarTender error message “An error occurred while loading the document . Please try again. Details: Permission Denied User: \IIS_WEBPRINT Action: Run Application Librarian Admin Console settings do not allow the specified user to perform this action.” and details how to fix the underlying problem that caused it to appear.
This error occurred using the Web Print feature in BarTender with security enabled and the security in the Web Administration Console set to Enable authentication over HTTP. The security for each user is set separately (not a part of a group).
Change the login account for the App Pool in the IIS server from local account (IIS_WEBPRINT) to a domain account with full Administrative rights on the computer.
Issue Found: BarTender 2016 R2