Capture App Start Errors

By default, the React Native SDK initializes the native SDK underneath the init method called on the JS layer. As a result, the SDK has a current limitation of not capturing native crashes that occur prior to the init method being called on the JS layer.

Starting with SDK version 8.0.0, you can initialize Sentry natively before JavaScript loads, enabling capture of app start errors and crashes that occur during:

• Native module initialization
• JavaScript bundle loading
• Early React Native bridge setup

This feature uses a sentry.options.json configuration file and native initialization APIs that read from this file.

Configuration File

Create a sentry.options.json file in your React Native project root with the same options you currently have in Sentry.init:

{
  "dsn": "https://key@example.io/value",
  "debug": true,
  "environment": "production",
  "tracesSampleRate": 1.0,
  "enableTracing": true
}

Android Setup

Initialize Sentry in your MainApplication class:

import io.sentry.react.RNSentrySDK

class MainApplication : Application(), ReactApplication {
    override fun onCreate() {
        super.onCreate()
        RNSentrySDK.init(this)
        // ... rest of your initialization code
    }
}

iOS Setup

Initialize Sentry in your AppDelegate before starting React Native so app start crashes are captured.

#import <RNSentry/RNSentry.h>

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [RNSentrySDK start];
    return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

@end

Expo Setup

If you're using Expo, you can enable native initialization using the Expo plugin. Add the useNativeInit option and your SDK options to the plugin configuration:

{
  "expo": {
    "plugins": [
      [
        "@sentry/react-native/expo",
        {
          "useNativeInit": true,
          "options": {
            "dsn": "https://key@example.io/value",
            "environment": "production",
            "tracesSampleRate": 1.0
          }
        }
      ]
    ]
  }
}

The plugin generates a sentry.options.json file from the options property during expo prebuild. If a sentry.options.json file already exists in your project root, the plugin options are merged into it (plugin options take precedence).

If you need to use environment variables or dynamic configuration, you can use app.config.js with the withSentry() wrapper instead of the array form in app.json:

import { withSentry } from "@sentry/react-native/expo";

export default withSentry(config, {
  useNativeInit: true,
  options: {
    dsn: "https://key@example.io/value",
    environment: "production",
    tracesSampleRate: 1.0,
  },
});

When useNativeInit is set to true, the Expo plugin automatically:

• Adds RNSentrySDK.init() to your Android MainApplication
• Adds RNSentrySDK.start() to your iOS AppDelegate

Setting the Environment

You can set the environment using the plugin options property as shown above, or using the SENTRY_ENVIRONMENT environment variable. The environment variable takes precedence over the plugin option.

For per-environment builds with EAS Build, set SENTRY_ENVIRONMENT in your build profiles:

{
  "build": {
    "production": {
      "env": { "SENTRY_ENVIRONMENT": "production" }
    },
    "staging": {
      "env": { "SENTRY_ENVIRONMENT": "staging" }
    }
  }
}