How can you determine how often your users experiences bugs? Whenever an erroroccurs, create a report containing the error that occurred and theassociated stacktrace. You can then send the report to an error trackingservice, such as Sentry, Fabric, or Rollbar.

The error tracking service aggregates all of the crashes your usersexperience and groups them together. This allows you to know how often yourapp fails and where the users run into trouble.

In this recipe, you’ll see how to report errors to the crash reporting service.

• Get a DSN from Sentry
• Import the Sentry package
• Create a
• Create a function to report errors
• Catch and report Dart errors
• Catch and report Flutter errors

1. Get a DSN from Sentry

Before reporting errors to Sentry, you’ll need a “DSN” to uniquely identifyyour app with the Sentry.io service.

• Create an account with Sentry
• Create a new app
• Copy the DSN

Import the package into the app. Thesentry package makes it easier to send error reports to the Sentryerror tracking service.

3. Create a SentryClient

Create a SentryClient. You’ll use the SentryClient to senderror reports to the sentry service.

final SentryClient _sentry = SentryClient(dsn: "App DSN goes Here");

With Sentry set up, you can begin to report errors. Since you don’t want toreport errors to Sentry during development, first create a function thatlets you know whether you’re in debug or production mode.

Next, use this function in combination with the SentryClient to reporterrors when the app is in production mode.

Future<void> _reportError(dynamic error, dynamic stackTrace) async {
  // Print the exception to the console
  print('Caught error: $error');
  if (isInDebugMode) {
    // Print the full stacktrace in debug mode
    print(stackTrace);
  } else {
    // Send the Exception and Stacktrace to Sentry in Production mode
    _sentry.captureException(
      exception: error,
    );
  }
}

5. Catch and report Dart errors

For this task, run your app inside a customZone. Zonesestablish an execution context for the code. This provides a convenient way tocapture all errors that occur within that context by providing an onErrorfunction.

In this case, you’ll run the app in a new Zone and capture all errors byproviding an callback.

In addition to Dart errors, Flutter can throw additional errors, such asplatform exceptions that occur when calling native code. You need to be sure tocapture and report these types of errors as well.

To capture Flutter errors, override theproperty. If you’re in debug mode, use a convenience functionfrom Flutter to properly format the error. If you’re in production mode, send the error to the onError callback defined in the previous step.

// This captures errors reported by the Flutter framework.
FlutterError.onError = (FlutterErrorDetails details) {
  if (isInDebugMode) {
    // In development mode, simply print to console.
    FlutterError.dumpErrorToConsole(details);
  } else {
    // In production mode, report to the application zone to report to
    // Sentry.
    Zone.current.handleUncaughtError(details.exception, details.stack);
};

Complete example