Specific JS fetch() fails on 0.66.4 (OR: How to debug react-native Android native code?)

New Version

0.66.4

Old Version

0.62.2

Build Target(s)

Android debug and release

Output of react-native info

$ react-native info
info Fetching system and libraries information...
(node:36495) Warning: Accessing non-existent property 'padLevels' of module exports inside circular dependency
(Use `node --trace-warnings ...` to show where the warning was created)
System:
    OS: macOS 11.6
    CPU: (8) x64 Intel(R) Core(TM) i7-1068NG7 CPU @ 2.30GHz
    Memory: 70.23 MB / 32.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 17.0.1 - /usr/local/bin/node
    Yarn: 1.22.1 - /usr/local/bin/yarn
    npm: 8.1.0 - /usr/local/bin/npm
    Watchman: 2021.11.01.00 - /usr/local/bin/watchman
  Managers:
    CocoaPods: 1.10.2 - /usr/local/bin/pod
  SDKs:
    iOS SDK:
      Platforms: DriverKit 21.0.1, iOS 15.0, macOS 12.0, tvOS 15.0, watchOS 8.0
    Android SDK: Not Found
  IDEs:
    Android Studio: 2020.3 AI-203.7717.56.2031.7583922
    Xcode: 13.1/13A1030d - /usr/bin/xcodebuild
  Languages:
    Java: 11.0.10 - /usr/bin/javac
  npmPackages:
    @react-native-community/cli: Not Found
    react: 17.0.2 => 17.0.2
    react-native: 0.66.4 => 0.66.4
    react-native-macos: Not Found
  npmGlobalPackages:
    *react-native*: Not Found

Issue and Reproduction Steps

I’m trying to call fetch in a specific point in my application, which succeeded in the previous version and the exact same call succeeds if I try it again and it happens every time. I don’t have a minimal reproducer and I’ve been debugging it for a few hours already.

I’ll note that it does work as expected on iOS.

I’m asking for some help on how to debug the actual react-native native code (not a module), I’ve found my way into sendReqeust() at ReactAndroid/src/main/java/com/facebook/react/modules/network/NetworkingModule.java.

The code does log on error:

    try {
      sendRequestInternal(...);
    } catch (Throwable th) {
      FLog.e(TAG, "Failed to send url request: " + url, th);
      final RCTDeviceEventEmitter eventEmitter = getEventEmitter("sendRequest error");
      if (eventEmitter != null) {
        ResponseUtil.onRequestError(eventEmitter, requestId, th.getMessage(), th);
      }
    }

but the logs never appear, I did try using FLog.setLoggingDelegate() on my react application class with my own delegate (that uses logcat), to no avail.

Ideally I’ll be able to debug react-native code with Android Studio, but since NPM ships a binary rather than source code, it’s not possible. I could dig further to try and understand how to compile the sources but it might take a while so I’m shooting my shot here.

Thanks.

[Avishayy]

Yes, thank you.

[Avishayy]

The fact that NPM ships a binary for ReactAndroid should not prevent you from debugging. If you place a breakpoint that should just work.

Android Studio doesn’t recognize that as part of the project’s code, so I can’t place breakpoints in it.

I’ll try the linked guide and keep you updated, thank you.