Use plain language. "You don't have permission to edit this report" is better than "Error 403."
Instead of a blank page or a cryptic code, show a "Helpful State": PogreЕЎka autorizacije
Always provide a primary action button like "Return to Dashboard" or "Go Back." Use plain language
If a user hits an authorization error multiple times, it might indicate a bug in your role assignments. PogreЕЎka autorizacije
"Your current account level doesn't allow access to this feature." Action: [Upgrade Plan] or [Contact Admin]