This example is a very small App Router site that shows the Exceptionless integration shape we want for a Next.js app: simple setup, rich metadata, and clear client/server error coverage.

• instrumentation-client.js for browser startup and navigation logging
• instrumentation.js for server startup and onRequestError
• app/error.jsx for route-level client render failures
• app/global-error.jsx for root-level client render failures
• app/api/demo/route.js for explicit server-side logging from a route handler

• Manual client logs with structured data
• Handled client exceptions submitted from a try/catch
• Unhandled client promise rejections captured by the browser global handler
• A client transition crash that lands in app/error.jsx
• A server route log enriched with request headers, IP, path, query string, and JSON body
• An unhandled route handler error captured by onRequestError
• A server component render error captured by onRequestError

This sticks to the native Next.js file boundaries instead of inventing another framework layer:

• instrumentation-client.js is where client-side monitoring starts before the app becomes interactive.
• instrumentation.js and onRequestError are where uncaught server render, route handler, server action, and proxy errors are captured.
• app/error.jsx and app/global-error.jsx stay responsible for client render failures inside the App Router.
• Route handlers submit logs directly with Exceptionless.createLog(...), the environment module memoizes Exceptionless.startup(...), and the server flushes with Exceptionless.processQueue() when needed.

• The server helper flushes the Exceptionless queue explicitly. That matters for short-lived serverless runtimes where a background timer may not get enough time to send queued events.
• The route handler uses after() so normal server logs flush after the response is sent.
• The example imports @exceptionless/browser and @exceptionless/node directly and uses the default Next.js bundler behavior, which is Turbopack on Next 16.
• Because this is a workspace example, you still need the root npm run build step before starting it locally so the SDK packages have fresh dist/ output.
• If we later package this for production ergonomics, the clean split is likely a very thin @exceptionless/nextjs helper for framework hooks plus an optional @exceptionless/vercel add-on for @vercel/otel, deployment metadata, and queue-flush helpers.

By default, the example uses the same local development Exceptionless project as the other samples:

c.apiKey = "LhhP1C9gijpSKCslHHCvwdSIz298twx271nTest";
c.serverUrl = "https://ex.dev.localhost:7111";

Set these env vars if you want the example to use a different project or server:

• NEXT_PUBLIC_EXCEPTIONLESS_API_KEY
• NEXT_PUBLIC_EXCEPTIONLESS_SERVER_URL
• EXCEPTIONLESS_API_KEY
• EXCEPTIONLESS_SERVER_URL

1. npm install
2. npm run build
3. cd example/nextjs
4. npm run dev