ErrorLens.ErrorHandling

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ErrorLens.ErrorHandlingProduction-Ready Error Handling for ASP.NET Core

Transform unhandled exceptions into clean, structured JSON responses with minimal setup — just two lines of code to get started.

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ErrorLens

Zero-Config Setup

Add two lines of code and every unhandled exception returns a structured JSON response — no configuration required.

Smart Error Codes

5 error code strategies — AllCaps, FullQualifiedName, KebabCase, PascalCase, DotSeparated — with full customization support.

Highly Configurable

JSON or YAML configuration for HTTP statuses, error codes, messages, and custom JSON field names.

Validation Support

Rich field-level, parameter-level, and global validation error responses with DataAnnotations integration.

Security Built-In

Automatic 5xx message sanitization prevents information disclosure. Startup validation catches misconfigurations early.

RFC 9457 Problem Details

Opt-in support for standardized application/problem+json format with automatic type URI generation.

Custom Handlers

Register IApiExceptionHandler implementations with priority ordering. Replace the built-in fallback handler for full control.

Response Customization

Add global properties like traceId, timestamp, or user context to all error responses via IApiErrorResponseCustomizer.

OpenTelemetry Tracing

Automatic Activity spans with error tags and OTel semantic conventions — zero new dependencies required.

Localization

Multi-language error messages via IStringLocalizer bridge. Error codes are used as resource keys in .resx files.

OpenAPI & Swagger

Auto-generated error response schemas for .NET 9+ OpenAPI and .NET 6-8 Swashbuckle integration.

Rate Limiting

Structured 429 responses with Retry-After headers via IRateLimitResponseWriter (.NET 7+).

FluentValidation Support

First-party integration for FluentValidation with automatic error code mapping, severity filtering, and structured field errors.

Quick Start ​

bash
dotnet add package ErrorLens.ErrorHandling
csharp
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddErrorHandling();

var app = builder.Build();
app.UseErrorHandling();
app.Run();

Any unhandled exception automatically becomes a structured JSON response:

json
{
  "code": "USER_NOT_FOUND",
  "message": "Could not find user with id 123"
}

Packages ​

PackageTargetNuGet
ErrorLens.ErrorHandling.NET 6 - 10NuGet
ErrorLens.ErrorHandling.OpenApi.NET 9+NuGet
ErrorLens.ErrorHandling.Swashbuckle.NET 6 - 8NuGet
ErrorLens.ErrorHandling.FluentValidation.NET 6 - 10NuGet

Released under the MIT License.

Copyright © 2026 ErrorLens