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CoreSystem.Http.ProblemDetails

Consistent RFC 9457 Problem Details for ASP.NET Core APIs.

CoreSystem.Http.ProblemDetails provides reusable exception-to-HTTP error handling for ASP.NET Core APIs on .NET 8, .NET 9 and .NET 10. It owns the HTTP mechanism while each application keeps its domain exceptions, business error codes, and mapping rules.

NuGet Downloads License .NET

Features

  • RFC 9457 application/problem+json responses
  • Application-owned exception mapping through IExceptionProblemMapper
  • Standard errorCode and traceId extensions
  • W3C Activity.Current.TraceId with HttpContext.TraceIdentifier fallback
  • Application-specific extensions through a callback
  • Exception type and message exposed only in Development

Installation

dotnet add package CoreSystem.Http.ProblemDetails

Quick Start

Implement the mapper in the API or Infrastructure layer. Domain and Application projects do not need to reference this package.

public sealed class ApiExceptionProblemMapper : IExceptionProblemMapper
{
    public ProblemDescriptor Map(Exception exception) => exception switch
    {
        OrderNotFoundException => new(404, "order_not_found", "Order not found", $"The order was not found."),
        _ => new(500, "internal_error", "Internal error", "An unexpected error occurred"),
    };
}

Register Problem Details and the mapper-backed exception handler:

builder.Services.AddCoreProblemDetails();
builder.Services.AddCoreExceptionHandler<ApiExceptionProblemMapper>();

var app = builder.Build();
app.UseExceptionHandler();

AddCoreExceptionHandler<TMapper>() registers the concrete mapper as scoped when it has not already been registered. Register any dependencies required by the mapper in the usual way. The exception handler creates a scope for each handled exception, so scoped mapper dependencies (such as a DbContext) are resolved and disposed correctly.

Refer to the full package README for the complete Quick Start example, including custom problem extensions and options.