How do you write a global filter in NestJS that handles both HttpException and unexpected errors differently?

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@Catch() export class AllExceptionsFilter implements ExceptionFilter { constructor(private readonly logger: LoggerService) {} catch(exception: unknown, host: ArgumentsHost) { const ctx = host.switchToHttp(); const res = ctx.getResponse(); const req = ctx.getRequest(); let status = 500; let message = 'Internal server error'; if (exception instanceof HttpException) { // Expected client error — expose details status = exception.getStatus(); const body = exception.getResponse(); message = typeof body === 'string' ? body : (body as any).message; } else { // Unexpected server error — log everything, expose nothing this.logger.error('Unexpected error', exception as Error); } res.status(status).json({ statusCode: status, message, path: req.url }); } } 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.

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.

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