What Your .NET Exceptions Are Telling Attackers (And How to Stop It)

How unhandled exceptions leak stack traces, connection strings, and internal architecture — and how to fix it properly in ASP.NET Core. Introduction: The Exception That Becomes a Roadmap Imagine you're building an API. A developer forgets to handle an edge case, and a request triggers an unhandled exception. What does the caller see? In a default ASP.NET Core project in development mode, they see something like this: System.NullReferenceException: Object reference not set to an instance of an object. at MyApi.Services.OrderService.GetOrderAsync(Int32 id) in /home/runner/work/MyApi/src/Services/OrderService.cs:line 47 at MyApi.Controllers.OrdersController.GetOrder(Int32 id) in /home/runner/work/MyApi/src/Controllers/OrdersController.cs:line 23 at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor... ConnectionString: Server=prod-db.internal;Database=orders;User=sa;Password=Sup3rS3cr3t! That response just told an attacker: Your internal folder structure and project layout The e