Expo not loading (React-Native) — null Expo SDK version

问题

My app was working till today but now it looks like something happened to version 18 of Expo.
I got this error:

The experience you requested uses Expo SDK v(null), but this copy of Expo Client requires at least v20.0.0. The author should update their experience to a newer Expo SDK version.

I then:

• Updated to Expo v20.0.0
• Handled all unmet dependencies
• yarn cache clean
• rm -rf node_modules/
• Reinstalled local node modules

and I'm still getting the same error.

What do I need to do to get Simulator to recognize that I am using the correct version of Expo?

Current environment:

• Expo v20.0.0
• react-native v0.47.0
• Node v8.11.1
• Xcode v9.3
• Mac OS v10.13.4

回答1:

Thanks to @PritishVaidya for helping me figure this out.
The problem was simply that I was missing "sdkVersion": "20.0.0" from my app.json. The use of this is lined out in the Expo Docs.

For example:

{
  "expo": {
    "name": "My app",
    "slug": "my-app",
    "sdkVersion": "20.0.0",
    "privacy": "public"
  }
}

来源：https://stackoverflow.com/questions/49721497/expo-not-loading-react-native-null-expo-sdk-version