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Preview troubleshooting

Most preview issues fall into one of these patterns. Pick the section that matches what you’re seeing.

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Web preview stuck on “Loading preview…”

If your web preview is stuck on “Loading preview…” and never loads, it’s likely because your app uses a native-only package like OneSignal (push notifications) that doesn’t work in the browser-based web preview.
Web preview stuck on Loading preview...
The fix is to build your app for a native simulator (iOS or Android) instead of using the web preview.

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How to Fix It

1

Switch to the iOS or Android tab

Click the iOS or Android tab at the top of the preview panel. You’ll see a Build simulator button at the bottom.
iOS tab with Build simulator button
2

Start the simulator build

Click Build simulator. In the Deploy panel that opens, make sure Simulator is selected, then click Build simulator.
Deploy panel with Simulator selected
3

Create an Expo account

The build process requires an Expo account. When prompted for your email or username, create a free account at expo.dev and enter your credentials.
Expo login prompt during build
4

Wait for the build to complete

The simulator build takes a few minutes. Once it’s done, your app will open in the simulator where you can test all native features including push notifications.

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Why Does This Happen?

The web preview runs your Expo app in a browser-based environment. Some packages – like OneSignal (push notifications) – rely on native iOS/Android APIs that don’t exist in the browser. When these packages try to initialize, the web preview gets stuck. Building for a native simulator creates a real native app that supports all native APIs, so everything works as expected.
This issue can also happen with other native-only packages. If your web preview is stuck and you’ve recently added a new package, try building for a native simulator to test your app.

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Changes don’t show on device or TestFlight

This usually means you’re looking at a different version of the app than the one your changes reached. Newly has three places your app can run – web preview, simulator, and TestFlight or the App Store – and they don’t always update at the same time. TestFlight uses the version of your app from your last build. Code changes don’t reach TestFlight until you start a new build. The full breakdown of which version contains what, and how to think about it: Preview vs builds. For a different class of issue – a fresh QR scan in Expo Go is still showing an old version – try force-closing Expo Go on your device and re-scanning the QR code from a clean start.

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Still stuck?

If none of the above fixes the issue:
  • Ask the AI to diagnose the problem – describe what you see and it can help debug.
  • Use the in-app support widget to reach out to support without leaving your project.
  • Email us at support@newly.app.