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My Project is 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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Still Stuck?

If the simulator build doesn’t resolve the issue: