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C# › Exception Handling

How would you design a robust global exception handling middleware in ASP.NET Core to convert unhandled exceptions into consistent API error responses?

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Answer

Register custom exception-handling middleware (or use the built-in UseExceptionHandler) early in the pipeline to catch ANY unhandled exception from later middleware/controllers, log it, and transform it into a consistent, structured error response (like the RFC 7807 Problem Details format) instead of leaking raw stack traces to API consumers.
app.UseExceptionHandler(errorApp => {
  errorApp.Run(async context => {
    var exceptionFeature = context.Features.Get<IExceptionHandlerFeature>();
    context.Response.StatusCode = 500;
    context.Response.ContentType = "application/problem+json";
    await context.Response.WriteAsJsonAsync(new {
      title = "An unexpected error occurred",
      status = 500,
      detail = app.Environment.IsDevelopment() ? exceptionFeature?.Error.Message : null
    });
  });
});
Real-world example Ensuring a production API never leaks internal stack traces or exception details to external clients, while still logging full details server-side.

Common follow-ups: Why is it important to conditionally hide exception details based on the environment (Development vs Production)?