Table of Contents
Introduction to Global Exception Handling
Global exception handling in ASP.NET Core ensures that unhandled exceptions are caught and managed gracefully. Instead of scattered try-catch blocks, you can centralize error handling, providing better logging, debugging, and user-friendly responses.
Why Use a Global Exception Handler?
A global exception handler helps in:
- Improving application stability
- Consistently formatting error responses
- Logging and tracking exceptions centrally
- Enhancing security by hiding sensitive details
Exception Handling with Middleware
ASP.NET Core provides built-in middleware for exception handling:
app.UseExceptionHandler("/Home/Error");
app.UseHsts();
Implementing a Global Exception Handler
We can use middleware to catch exceptions globally and return meaningful responses.
public class GlobalExceptionMiddleware
{
private readonly RequestDelegate _next;
private readonly ILogger<GlobalExceptionMiddleware> _logger;
public GlobalExceptionMiddleware(RequestDelegate next, ILogger<GlobalExceptionMiddleware> logger)
{
_next = next;
_logger = logger;
}
public async Task Invoke(HttpContext context)
{
try
{
await _next(context);
}
catch (Exception ex)
{
_logger.LogError($"Unhandled Exception: {ex}");
context.Response.StatusCode = 500;
await context.Response.WriteAsync("An unexpected error occurred. Please try again later.");
}
}
}
Register the middleware in `Program.cs`:
app.UseMiddleware<GlobalExceptionMiddleware>();
Structured Logging for Exceptions
Integrating structured logging with Serilog helps in better exception tracking.
Log.Logger = new LoggerConfiguration()
.WriteTo.Console()
.WriteTo.File("logs/errors.txt", rollingInterval: RollingInterval.Day)
.CreateLogger();
Handling Specific Exceptions
We can catch and handle specific exceptions like `UnauthorizedAccessException`.
public class CustomExceptionMiddleware
{
private readonly RequestDelegate _next;
public CustomExceptionMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task Invoke(HttpContext context)
{
try
{
await _next(context);
}
catch (UnauthorizedAccessException ex)
{
context.Response.StatusCode = 401;
await context.Response.WriteAsync("Unauthorized Access");
}
catch (Exception ex)
{
context.Response.StatusCode = 500;
await context.Response.WriteAsync("An internal server error occurred.");
}
}
}
Creating a Custom Exception Middleware
For complex applications, use custom exception middleware to structure error responses:
app.UseMiddleware<CustomExceptionMiddleware>();
Performance Considerations
Best practices for efficient error handling:
- Minimize exception logging overhead
- Use caching where applicable
- Ensure async exception handling
Conclusion
Global exception handling in ASP.NET Core simplifies error management, improves logging, and ensures consistency. By leveraging middleware and structured logging, developers can build robust applications with minimal error exposure.