[Android] Error: Duplicate resources

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Environment

React Native Environment Info:

System:
  OS: macOS 10.14
  CPU: (4) x64 Intel(R) Core(TM) i5-7267U CPU @ 3.10GHz
  Memory: 103.10 MB / 8.00 GB
  Shell: 3.2.57 - /bin/bash
Binaries:
  Node: 8.12.0 - /usr/local/bin/node
  Yarn: 1.0.1 - /usr/local/bin/yarn
  npm: 6.4.1 - /usr/local/bin/npm
  Watchman: 4.7.0 - /usr/local/bin/watchman
SDKs:
  iOS SDK:
    Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
  Android SDK:
    API Levels: 16, 17, 19, 21, 23, 24, 25, 26, 27, 28
    Build Tools: 19.1.0, 20.0.0, 23.0.1, 23.0.2, 23.0.3, 25.0.0, 25.0.1, 25.0.2, 25.0.3, 26.0.0, 26.0.1, 26.0.2, 26.0.3, 27.0.0, 27.0.1, 27.0.3, 28.0.0, 28.0.0, 28.0.2, 28.0.3
    System Images: android-16 | ARM EABI v7a, android-16 | MIPS, android-16 | Intel x86 Atom, android-16 | Google APIs Intel x86 Atom, android-19 | Google APIs Intel x86 Atom, android-24 | Google Play Intel x86 Atom, android-26 | Google APIs Intel x86 Atom, android-26 | Google APIs Intel x86 Atom_64, android-26 | Google Play Intel x86 Atom, android-27 | Google Play Intel x86 Atom, android-28 | Google APIs Intel x86 Atom, android-P | Google APIs Intel x86 Atom, android-P | Google Play Intel x86 Atom
IDEs:
  Android Studio: 3.2 AI-181.5540.7.32.5056338
  Xcode: 10.1/10B61 - /usr/bin/xcodebuild
npmPackages:
  react: 16.6.0-alpha.8af6728 => 16.6.0-alpha.8af6728 
  react-native: 0.57.4 => 0.57.4 
npmGlobalPackages:
  babel-preset-react-native: 4.0.0
  react-native-cli: 2.0.1
  react-native-create-library: 3.1.2
  react-native-git-upgrade: 0.2.7

Description

I’m not able to create a release apk with the PNG image in Android. But can able to create a release apk when there is no PNG image in it. Here is the error I’m getting while generating the release build

[drawable-mdpi-v4/assets_mario] /Users/jeffreyrajan/Tutorials/RN/errorCheck/android/app/src/main/res/drawable-mdpi/assets_mario.png	[drawable-mdpi-v4/assets_mario] /Users/jeffreyrajan/Tutorials/RN/errorCheck/android/app/build/generated/res/react/release/drawable-mdpi-v4/assets_mario.png: Error: Duplicate resources
:app:mergeReleaseResources FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:mergeReleaseResources'.
> [drawable-mdpi-v4/assets_mario] /Users/jeffreyrajan/Tutorials/RN/errorCheck/android/app/src/main/res/drawable-mdpi/assets_mario.png	[drawable-mdpi-v4/assets_mario] /Users/jeffreyrajan/Tutorials/RN/errorCheck/android/app/build/generated/res/react/release/drawable-mdpi-v4/assets_mario.png: Error: Duplicate resources

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

Reproducible Demo

1. Create a app - react-native init demo
2. Create a assets folder in the project root folder.
3. Add a PNG image inside the assets folder.
4. Now implement a image component with the above PNG image.
5. Now bundle it using the cmd react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res/
6. Then generate release apk using Generate Signed APK

[echaritonidis]

Mapsy’s answer should help https://stackoverflow.com/a/52750886 So basically you edit the /node_modules/react-native/react.gradle file and add the doLast right after the doFirst block, manually.

doFirst { ... }
doLast {
    def moveFunc = { resSuffix ->
        File originalDir = file("$buildDir/generated/res/react/release/drawable-${resSuffix}");
        if (originalDir.exists()) {
            File destDir = file("$buildDir/../src/main/res/drawable-${resSuffix}");
            ant.move(file: originalDir, tofile: destDir);
        }
    }
    moveFunc.curry("ldpi").call()
    moveFunc.curry("mdpi").call()
    moveFunc.curry("hdpi").call()
    moveFunc.curry("xhdpi").call()
    moveFunc.curry("xxhdpi").call()
    moveFunc.curry("xxxhdpi").call()
}

[rahulkumar1409]

Remove the files you might have on:

android/app/src/main/res/drawable-mdpi/ android/app/src/main/res/drawable-xhdpi/ android/app/src/main/res/drawable-xxhdpi/ Run Build again, This fixed the issue for me.