Invariant Violation: "trackerApp" has not been registered

i struggle since a several days with the following error:

 **Invariant Violation: "trackerApp" has not been registered. This can happen if:* Metro (the local dev server) is run from the wrong folder. Check if Metro is running, stop it and restart it in the current project.* A module failed to load due to an error and `AppRegistry.registerComponent` wasn't called.**

i check everything, but nothing worked.

Code in app.json

{"name": "trackerApp","displayName": "trackerApp"}

Code in index.js

import {AppRegistry} from 'react-native';import App from './App';// import {name as appName} from './app.json';import { name as appName } from "./app.json";// import App from "./src/App.tsx";// Register the serviceAppRegistry.registerComponent(appName, () => App);