> ## Documentation Index > Fetch the complete documentation index at: https://docs.appsignal.com/llms.txt > Use this file to discover all available pages before exploring further. # Troubleshooting browser monitoring Browser monitoring is a beta [AppSignal Labs](/labs) feature. The `@appsignal/browser` package is published under the `beta` tag on npm, and its configuration and API may still change between beta releases. Share feedback in our [Discord community](https://discord.gg/EjF6ykYx63). ## No data arrives at all Work through these in order. Each one is a complete stop: nothing is sent when it applies. 1. **`active` resolves to `false`.** Log the value you pass, rather than the expression. A bundler that does not replace `process.env.NODE_ENV` leaves the comparison `false` in the browser. 2. **`init()` never ran.** Setting configuration is not enough. Confirm the module that calls `init()` is actually imported by your entry point, and that a tree-shaking build has not dropped it. 3. **The key is wrong.** A wrong key returns `401`. Check you are using the [Front-end API key](/browser/installation#find-your-front-end-api-key), not one of the Push keys, and that it belongs to this app rather than your staging or production one. 4. **Requests are blocked.** Open your browser's network panel and look for a request to `/ingest/browser/errors` for errors, or `/ingest/browser` for web vitals. A blocked request shows as a Content Security Policy violation in the console: add `https://appsignal-endpoint.net` to your `connect-src` directive. 5. **`endpoint` is not set.** With no `endpoint`, the SDK posts to the current origin, which only works if you proxy AppSignal traffic through your own domain. Set it to `https://appsignal-endpoint.net` otherwise. ## Errors arrive, web vitals do not Web vitals are batched, not sent per measurement. They are sent when the page is hidden, when it is closed, and on a client-side route change. Navigate away or switch tabs, then check the Performance view again. If they still do not appear, check whether the missing metrics are CLS and INP specifically. Those two are [Chromium-only](/browser/web-vitals#browser-support). ## An error is missing * **It happened before `init()` ran.** Nothing that throws before then is captured. Import your AppSignal setup as the first import in your entry point. * **It was a repeat.** Check the [rate limits](/browser/error-tracking#rate-limits) on identical and total errors. * **It was sampled out.** Check whether `errors.sampleRate` is below `1.0`. * **`beforeError` dropped it.** A callback that returns anything falsy drops the error. Log the event at the top of the callback to confirm what it receives. * **It was thrown inside an [iframe](/browser/error-tracking#errors-that-are-not-reported).** A same-origin iframe needs its own `init()` call. * **It was a React render error.** React does not let render errors reach `window`. Add an [error boundary](/browser/react). * **It came from a script on another domain.** Read the following section. ## Errors show up with no message or stack If your JavaScript is served from a CDN and no errors arrive at all, this is the usual cause. The browser hides the details of errors from scripts on another domain, leaving only the message `Script error.`, and the SDK throws those away. Fix it by serving those scripts with CORS headers, as described in [assets hosted on a CDN](/browser/installation#assets-hosted-on-a-cdn). ## Backtraces are minified Backtraces are resolved with [sourcemaps](/front-end/sourcemaps), matched on the revision string. Set `appVersion` to the same value your build uses for its sourcemaps. Without `appVersion`, there is nothing to match on and backtraces stay minified. ## One route produces hundreds of error groups The [route template](/browser/installation#report-the-current-route) is missing, so each URL groups on its own. Call `setRouteTemplate("/orders/:id")` on every router navigation, and errors regroup from that deploy onwards. The Performance view has the same problem, where it also counts against the ingestion limit on distinct routes. ## Client-side navigation is not reported The SDK and most routers both patch `history.pushState`. The SDK composes with a patch that is already installed, but a router that loads first and replaces the SDK's patch breaks the chain. Import your AppSignal setup before your router. Hash routers are only treated as routers when the hash looks like a route, such as `#/orders`. A bare `#orders` hash is indistinguishable from an in-page anchor and is not treated as a navigation. ## Network breadcrumbs have no timings The request was cross-origin and the server sent no `Timing-Allow-Origin` header. Read more in [reading network breadcrumbs](/browser/breadcrumbs#reading-network-breadcrumbs). ## Getting help Include your app name, the `@appsignal/browser` version, and the browser and version where you see the problem. Reach us through [our support channels](/support), or in our [Discord community](https://discord.gg/EjF6ykYx63) for beta feedback.