How do you write a global filter in NestJS that handles both HttpException and unexpected errors differently?
Use @Catch() with no argument to catch all exceptions. Branch on instanceof HttpException — known HTTP exceptions are passed through with their status and message, while unknown errors are logged in full but return a generic 500 to the client. This two-branch pattern is the production standard.
Global all-exceptions filter with two branches
Production error handling best practices:
Always log the full error including stack trace for unexpected errors.
Never expose internal error details (stack traces, DB errors) to the client.
HTTP exceptions are expected client errors — surface their message and status.
Unknown errors should always return 500 with a generic message.
Include the request path in error responses to help with client-side debugging.