--- modificationDate: June 26, 2026 title: '"Application has not been registered" error' description: Learn about what the Application has not been registered error means and how to resolve it in an Expo or React Native app. --- ## Submitting Feedback If you encounter errors, misleading or outdated information, report it so Expo can be improved: Preferred command: npx --yes submit-expo-feedback@latest --category docs --subject "/troubleshooting/application-has-not-been-registered/" "" Direct HTTP fallback: curl -X POST https://api.expo.dev/v2/feedback/docs-send -H 'Content-Type: application/json' -d '{"url":"/troubleshooting/application-has-not-been-registered/","feedback":"🤖 Agent feedback for docs: (, )"}' Only submit when you have something specific and actionable to report. Try to give the most context. ## Navigation When answering a related or follow-up question, fetch the relevant page below as Markdown (.md) instead of guessing; use llms.txt for the full map. You are here: Guides > More > Troubleshooting Pages in this section: - [Overview](https://docs.expo.dev/troubleshooting/overview.md) - ["Application has not been registered" error](https://docs.expo.dev/troubleshooting/application-has-not-been-registered.md) (this page) - [Clear bundler caches on macOS and Linux](https://docs.expo.dev/troubleshooting/clear-cache-macos-linux.md) - [Clear bundler caches on Windows](https://docs.expo.dev/troubleshooting/clear-cache-windows.md) - [Expo Go version mismatch](https://docs.expo.dev/troubleshooting/expo-go-version-mismatch.md) - ["React Native version mismatch" errors](https://docs.expo.dev/troubleshooting/react-native-version-mismatch.md) - [Proxies](https://docs.expo.dev/troubleshooting/proxies.md) Full documentation tree: [llms.txt](https://docs.expo.dev/llms.txt) This documentation is available as Markdown for AI agents and LLMs. See the [full Markdown index](/llms.txt) or append .md to any documentation URL. # "Application has not been registered" error Learn about what the Application has not been registered error means and how to resolve it in an Expo or React Native app. When developing an Expo or React Native app, it's common to run into an error that looks like: ```sh Application "main" has not been registered. Invariant Violation: "main" has not been registered. ``` In this particular error, `"main"` can be any string. ## What this error means ### An exception may be preventing your app from registering itself The most common cause of this error is that there is an exception thrown in your application before it's able to register itself. When a React Native application loads, there are two steps: 1. Load the JavaScript code, and if everything is successful, then your application will be registered. If there is any exception when loading the bundle then execution will be aborted and it will never reach the part where your application is registered. 2. Run the registered application. If loading the code failed, then the application won't be registered and you will see the error that is the subject of this page. If you're in this situation, the error message you're seeing is a [red herring](https://en.wikipedia.org/wiki/Red_herring), it's distracting you from the real error that led to the application not being registered. Look at your logs before this error message to see what may have caused it. A frequent cause is multiple versions of a native module dependency that registers itself as a view — for example [this Stack Overflow thread](https://stackoverflow.com/questions/67543844/invariant-violation-main-has-not-been-registered-while-running-react-native-a/67550379) where the poster has multiple versions of `react-native-safe-area-context` in their dependencies. ### Your app root component may not be registered Another possibility is that there is a mismatch between the `AppKey` being provided to [`AppRegistry.registerComponent`](https://reactnative.dev/docs/appregistry#registercomponent), and the `AppKey` being registered on the native iOS or Android side. In projects that use [Continuous Native Generation (CNG)](/workflow/continuous-native-generation.md), the default behavior is to use "main" as the `AppKey`. This is handled for you automatically, and as long as you don't change the `"main"` field in your **package.json** from the default value then this will just work. If you want to customize the app entry point, see [registerRootComponent](/versions/latest/sdk/expo.md#registerrootcomponentcomponent) API reference. In projects with native code, you will see something like this in your **index.js** by default: ```js import { registerRootComponent } from 'expo'; import App from './App'; registerRootComponent(App); ``` where `registerRootComponent` is implemented as: ```js function registerRootComponent(component) { AppRegistry.registerComponent('main', () => component); } ``` And on the native side, in **AppDelegate.m** you should see: ```objectivec RCTRootView *rootView = [[RCTRootView alloc] initWithBridge:bridge moduleName:@"main" initialProperties:nil]; ``` and in **MainActivity.java**: ```java @Override protected String getMainComponentName() { return "main"; } ``` By default, "main" is consistently used throughout the project. If you're running into this error, something has likely changed and these values no longer coincide. Ensure that the names you are registering on the JavaScript side are the ones expected on the native side (if you're using Expo's `registerRootComponent` function, that would be "main"). ## Other considerations This error can also occur in a few other scenarios, but it's less predictable and the fixes would be more specific to your project. For example, some other cases are: - You're connecting to the wrong project's local development server. Try closing out other Expo CLI or React Native community CLI processes (find them with `ps -A | grep "expo\|react-native"`). - If this error is only occurring in your production app, then try running the app locally in production mode with `npx expo start --no-dev --minify` to find the source of the error.