Using Sentry

A guide on installing and configuring Sentry for crash reporting.

Sentry is a crash reporting platform that provides you with "real-time insight into production deployments with info to reproduce and fix crashes".

It notifies you of exceptions or errors that your users run into while using your app, and organizes them for you on a web dashboard. Reported exceptions include stacktraces, device info, version, and other relevant context automatically; you can also provide additional context that is specific to your application, like the current route and user id.

Why sentry-expo?

• Sentry treats React Native as a first-class citizen and we have collaborated with Sentry to make sure Expo is, too.
• It's very easy to set up and use
• It scales to meet the demands of even the largest projects.
• We trust it for our projects at Expo.
• It is free for up to 5,000 events per month.
• It streamlines your error-reporting code across iOS, Android, and web

Native crash reporting is not available in Expo Go, it is only available in standalone builds or development builds.

Platform compatibility

Installing and configuring Sentry

import * as Sentry from 'sentry-expo';

Sentry.init({
  dsn: 'YOUR DSN HERE',
  enableInExpoDevelopment: true,
  debug: true, // If `true`, Sentry will try to print out useful debugging information if something goes wrong with sending the event. Set it to `false` in production
});

// Access any @sentry/react-native exports via:
// Sentry.Native.*

// Access any @sentry/browser exports via:
// Sentry.Browser.*

// The following example uses `captureException()` from Sentry.Native.* to capture errors:
try {
  // your code
} catch (error) {
  Sentry.Native.captureException(error);
}

import * as Sentry from '@sentry/react-native';

Sentry.init({
  dsn: 'YOUR DSN',
});

{
  "expo": {
    %%placeholder-start%%... your existing configuration %%placeholder-end%%
    "hooks": {
      "postPublish": [
        {
          "file": "sentry-expo/upload-sourcemaps",
          "config": {
            "organization": "sentry org slug, or use the `SENTRY_ORG` environment variable",
            "project": "sentry project name, or use the `SENTRY_PROJECT` environment variable"
          }
        }
      ]
    }
  }
}

{
  "expo": {
    "plugins": ["sentry-expo"]
    %%placeholder-start%%... your existing configuration %%placeholder-end%%
  }
}

Source Maps

With the postPublish hook in place, now all you need to do is run expo publish and the source maps will be uploaded automatically. We automatically assign a unique release version for Sentry each time you hit publish, based on the version you specify in app.json and a release id on our backend -- this means that if you forget to update the version but hit publish, you will still get a unique Sentry release.

This hook can also be used as a postExport hook if you're self-hosting your updates.

Uploading source maps at build time

With expo-updates, release builds of both iOS and Android apps will create and embed a new update from your JavaScript source at build-time. This new update will not be published automatically and will exist only in the binary with which it was bundled. Since it isn't published, the source maps aren't uploaded in the usual way like they are when you run expo publish (actually, we are relying on Sentry's native scripts to handle that). Because of this you have some extra things to be aware of:

• Your release will automatically be set to Sentry's expected value- ${bundleIdentifier}@${version}+${buildNumber} (iOS) or ${androidPackage}@${version}+${versionCode} (Android).
• Your dist will automatically be set to Sentry's expected value: ${buildNumber} (iOS) or ${versionCode} (Android).
• The configuration for build time source maps comes from the android/sentry.properties and ios/sentry.properties files. For more information, see Sentry's documentation. Manual configuration is only required for bare projects, the sentry-expo config plugin handles it otherwise.
• Configuration for expo publish and npx expo export for projects is done via app.json, whether using bare workflow or not.

Skipping or misconfiguring either of these can lead to invalid source maps, and you won't see human-readable stacktraces in your errors.

Uploading source maps for updates

This requires SDK 47, with sentry-expo@6.0.0 or above and expo-updates@0.15.5 or above.

If you're using EAS Update, or if you're self-hosting your updates (this means you run npx expo export manually), you need to take the following steps to upload the source maps for your update to Sentry:

• Run eas update. This will generate a dist folder in your project root, which contains your JavaScript bundles and source maps. This command will also output the 'Android update ID' and 'iOS update ID' that we'll need in the next step.
• Copy or rename the bundle names in the dist/bundles folder to match index.android.bundle (Android) or main.jsbundle (iOS).
• Next, you can use the Sentry CLI to upload your bundles and source maps:
  • release name should be set to ${bundleIdentifier}@${version}+${buildNumber} (iOS) or ${androidPackage}@${version}+${versionCode} (Android), so for example com.domain.myapp@1.0.0+1.
  • dist should be set to the Update ID that eas update generated.

For more information, see Sentry's instructions for uploading the bundle and source maps.

The steps above define a new 'dist' on Sentry, under the same release as your full app build, and associate the source maps with this new dist. If you want to customize this behavior, you can pass in your own values for release and dist when you initialize Sentry in your code. For example:

import * as Sentry from 'sentry-expo';
import * as Updates from 'expo-updates';

Sentry.init({
  dsn: 'YOUR DSN',
  release: 'my release name',
  dist: 'my dist',
});

These values should match the values you pass to the sentry-cli when uploading your source maps.

Testing Sentry

When building tests for your application, you want to assert that the right flow-tracking or error is being sent to Sentry, but without really sending it to Sentry servers. This way you won't swamp Sentry with false reports during test running and other CI operations.

sentry-testkit enables Sentry to work natively in your application, and by overriding the default Sentry transport mechanism, the report is not really sent but rather logged locally into memory. In this way, the logged reports can be fetched later for your own usage, verification, or any other use you may have in your local developing/testing environment.

For more information on how to get started, see sentry-testkit documentation.

If you're using jest, make sure to add @sentry/.* and sentry-expo to your transformIgnorePatterns.

Error reporting semantics

In order to ensure that errors are reported reliably, Sentry defers reporting the data to their backend until the next time you load the app after a fatal error rather than trying to report it upon catching the exception. It saves the stacktrace and other metadata to AsyncStorage and sends it immediately when the app starts.

Disabled by default in dev

Unless enableInExpoDevelopment: true is set, all your dev/local errors will be ignored and only app releases will report errors to Sentry. You can call methods like Sentry.Native.captureException(new Error('Oops!')) but these methods will be no-op.

Troubleshooting

import * as Sentry from 'sentry-expo';
import * as Network from 'expo-network';

const devServerPort = 8081;
let devServerIpAddress: string | null = null;
Network.getIpAddressAsync().then(ip => {
  devServerIpAddress = ip;
});

Sentry.init({
  tracesSampleRate: 1.0,
  integrations: [
    new Sentry.Native.ReactNativeTracing({
      shouldCreateSpanForRequest: url => {
        return !__DEV__ || !url.startsWith(`http://${devServerIpAddress}:${devServerPort}/logs`);
      },
    }),
  ],
});

Learn more about Sentry

Sentry does more than just catch fatal errors, learn more about how to use Sentry from their JavaScript usage docs.