TypeError: Network request failed when using fetch in Android

[yim-jj]

Description

1. Fetch request fails only on Android, succeeds on iOS.
2. Fails only on my team servers. Success on other servers. So, I changed https to http (my team server and client) and it succeeded.
3. Same problem with axios.
4. android:usesCleartextTraffic="true" => Also not helpful
5. Flipper ...?? React Native 0.62.* [TypeError: Network request failed] on file upload #28551 => Also not helpful

React Native version:

System:
OS: macOS 11.3
CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
Memory: 731.05 MB / 16.00 GB
Shell: 5.8 - /bin/zsh
Binaries:
Node: 14.15.1 - /usr/local/bin/node
Yarn: 1.22.10 - /usr/local/bin/yarn
npm: 7.10.0 - /usr/local/bin/npm
Watchman: 4.9.0 - /usr/local/bin/watchman
Managers:
CocoaPods: 1.10.1 - /usr/local/bin/pod
SDKs:
iOS SDK:
Platforms: iOS 14.4, DriverKit 20.2, macOS 11.1, tvOS 14.3, watchOS 7.2
Android SDK: Not Found
IDEs:
Android Studio: 4.1 AI-201.8743.12.41.7199119
Xcode: 12.4/12D4e - /usr/bin/xcodebuild
Languages:
Java: 11.0.10 - /usr/bin/javac
npmPackages:
@react-native-community/cli: Not Found
react: 17.0.1 => 17.0.1
react-native: 0.64.0 => 0.64.0
react-native-macos: Not Found
npmGlobalPackages:
react-native: Not Found

Steps To Reproduce

1. set up project
   npx react-native init AwesomeTSProject --template react-native-template-typescript

2. App.tsx
   async function helloServer() {
   try {
   const response = await fetch("https://www.*****.com/greeter/hello", {
   headers: new Headers({ "Content-Type": "application/json" }),
   });

   const json = await response.json();

   console.log(json);
   } catch (error) {
   console.log(error);
   }
   }

export default function App() {
useEffect(() => {
helloServer();
}, []);

return (

Open up App.tsx to start working on your app!

);
}

3. npm run android (test with device)

Expected Results

Server response should be logged.

[yim-jj]

It was a SSL certificate issue. :(

[ak2403]

Same issue exists. The API call is working in a real device, but not in the emulator.

Now, my concern is, Should I worry that it doesn't work on emulator? It will be good if someone can answer this question, so that I can work with the real device until this issue is sorted out.