--- name: build-fix description: Diagnose and fix Flutter build failures, including dependency conflicts, Gradle errors, compilation issues, and platform-specific build problems. Use when builds fail locally or in CI. --- # Build Failure Diagnosis and Fix Skill Expert guidance for diagnosing and fixing Flutter build failures in Android projects, including dependency conflicts, Gradle errors, and compilation issues. ## When to Use This Skill - Flutter build fails (`flutter build apk` or `flutter build appbundle`) - Gradle sync/build errors - Dependency resolution failures - Compilation errors (Dart or Kotlin/Java) - Native build failures - Plugin integration issues - Version conflicts ## Build Failure Diagnostic Workflow ### Step 1: Identify the Build Stage Flutter Android builds go through several stages: 1. **Dependency Resolution** (`flutter pub get`) 2. **Dart Compilation** (`flutter build`) 3. **Gradle Configuration** (Android build system setup) 4. **Resource Processing** (R8, ProGuard, resources) 5. **Native Compilation** (Kotlin/Java code) 6. **Packaging** (APK/AAB creation) Identify which stage is failing to narrow down the issue. ### Step 2: Clean Build First **Always try a clean build first**: ```bash # Nuclear option - clean everything flutter clean cd android ./gradlew clean cd .. rm -rf ~/.gradle/caches # Only if really stuck flutter pub get flutter build apk --verbose ``` ### Step 3: Analyze Error Messages Look for key error patterns: - **Gradle**: "BUILD FAILED", "Could not resolve", "Deprecated" - **Dart**: "Error:", "Warning:", "Unhandled exception" - **R8/ProGuard**: "shrinking", "Missing class" - **Dependencies**: "version conflict", "incompatible" ## Common Build Failures and Solutions ### 1. Dependency Conflicts #### Issue: Version Conflicts ``` Error: Version conflict between dependencies ``` **Diagnosis**: ```bash cd android ./gradlew app:dependencies ``` **Solution**: - Review `pubspec.yaml` - update conflicting dependencies - Check `android/app/build.gradle.kts` for Android dependency versions - Use version ranges carefully: `^1.0.0` vs `>=1.0.0 <2.0.0` - Run `flutter pub upgrade --major-versions` if needed #### Issue: Missing Dependencies ``` Error: Could not find dependency ``` **Solution**: - Check dependency name spelling in `pubspec.yaml` - Verify dependency exists on pub.dev - Check internet connection - Clear pub cache: `flutter pub cache repair` ### 2. Gradle Build Errors #### Issue: Gradle Version Incompatibility ``` Error: Gradle version X.X is required ``` **Solution**: - Update Gradle wrapper: `cd android && ./gradlew wrapper --gradle-version=8.0` - Check `android/gradle/wrapper/gradle-wrapper.properties` - Ensure Java 17 is installed: `java -version` #### Issue: Gradle Daemon Issues ``` Error: Gradle daemon stopped unexpectedly ``` **Solution**: - Stop daemon: `cd android && ./gradlew --stop` - Clear Gradle cache: `rm -rf ~/.gradle/caches` - Check memory settings in `gradle.properties` - For CI, use `android/gradle-ci.properties` #### Issue: Deprecated Gradle Configuration ``` Warning: The following Gradle features are deprecated ``` **Solution**: - Review `android/build.gradle.kts` and `android/app/build.gradle.kts` - Update Gradle plugin version - Check for deprecated DSL usage - Run `./gradlew --warning-mode all` for details ### 3. Java/JVM Issues #### Issue: Wrong Java Version ``` Error: Compilation failed: java.lang.UnsupportedClassVersionError ``` **Solution**: - This project requires Java 17 - Check: `java -version` - Set JAVA_HOME: `export JAVA_HOME=/path/to/java17` - Verify in gradle files: `JavaVersion.VERSION_17` #### Issue: Out of Memory ``` Error: GC overhead limit exceeded ``` **Solution**: - Increase heap size in `android/gradle.properties`: ```properties org.gradle.jvmargs=-Xmx4g -XX:MaxMetaspaceSize=1g ``` - For CI, use `android/gradle-ci.properties` (3GB limit) - Enable parallel GC: `-XX:+UseParallelGC` ### 4. R8/ProGuard Issues #### Issue: Class Not Found After R8 Shrinking ``` Error: Missing class referenced from: ... ``` **Solution**: - Add ProGuard rules in `android/app/proguard-rules.pro`: ```proguard -keep class com.your.package.** { *; } -dontwarn com.problematic.library.** ``` - Check if library provides ProGuard rules - Disable shrinking temporarily to test: `shrinkResources false` #### Issue: R8 Fails ``` Error: R8 task failed ``` **Solution**: - Update Android Gradle Plugin - Check for incompatible ProGuard rules - Try R8 full mode: `android.enableR8.fullMode=true` - Use `--verbose` flag to see details ### 5. Native Code Issues #### Issue: Kotlin Compilation Fails ``` Error: Kotlin compilation failed ``` **Solution**: - Check Kotlin version in `android/build.gradle.kts` - Review Kotlin code in `android/app/src/main/kotlin/` - Ensure Kotlin plugin version matches Gradle - Update to latest stable Kotlin version #### Issue: NDK/Native Library Issues ``` Error: Could not find NDK ``` **Solution**: - Install NDK via Android Studio or SDK Manager - Set `ANDROID_NDK_HOME` environment variable - Check if dependency actually needs NDK - Consider excluding unwanted ABIs in `build.gradle.kts` ### 6. Resource Issues #### Issue: Duplicate Resources ``` Error: Duplicate resources ``` **Solution**: - Check `android/app/src/main/res/` for duplicates - Review resource merging in `build.gradle.kts` - Use resource prefixes to avoid conflicts - Exclude duplicates from dependencies #### Issue: Missing Resources ``` Error: Resource not found ``` **Solution**: - Verify resource files exist in correct folders - Check resource naming (lowercase, no special chars) - Ensure resources are in appropriate density folders - Run `flutter pub get` to regenerate ### 7. Plugin Integration Issues #### Issue: Plugin Registration Fails ``` Error: Unhandled Exception: MissingPluginException ``` **Solution**: - Run `flutter clean && flutter pub get` - Check `.flutter-plugins-dependencies` - Verify plugin in `pubspec.yaml` - Rebuild native code: `flutter build apk --verbose` #### Issue: Plugin Version Conflict ``` Error: Plugin version incompatible ``` **Solution**: - Check plugin's minimum Flutter/Android versions - Update Flutter SDK if needed - Update plugin to compatible version - Review plugin's changelog for breaking changes ### 8. Manifest Issues #### Issue: Manifest Merge Fails ``` Error: Manifest merger failed ``` **Solution**: - Check `android/app/src/main/AndroidManifest.xml` - Review plugin manifests causing conflicts - Add merge rules if needed: ```xml ``` - Use `tools:replace` or `tools:merge` attributes #### Issue: Permission Issues ``` Error: Permission denied ``` **Solution**: - Add required permissions to `AndroidManifest.xml` - Check permission compatibility with minSdkVersion - Review runtime permission handling in code ## Project-Specific Build Configuration ### This Template Uses - **Java 17**: Required for optimal performance - **Gradle 8.0+**: Modern build system - **Flutter 3.10.1+**: Latest stable features - **Kotlin**: For Android native code - **R8**: Code shrinking enabled - **Parallel builds**: Optimized for performance - **Build cache**: Enabled for faster rebuilds ### Key Files 1. **pubspec.yaml**: Flutter dependencies 2. **android/build.gradle.kts**: Root Gradle config 3. **android/app/build.gradle.kts**: App-specific Gradle config 4. **android/gradle.properties**: Local build settings 5. **android/gradle-ci.properties**: CI-optimized settings 6. **android/app/src/main/AndroidManifest.xml**: App manifest ## Systematic Debug Approach ### Level 1: Quick Fixes (Try First) ```bash flutter clean flutter pub get flutter build apk --verbose ``` ### Level 2: Gradle Reset ```bash cd android ./gradlew clean ./gradlew --stop cd .. flutter clean flutter pub get flutter build apk --verbose ``` ### Level 3: Cache Clear ```bash flutter clean rm -rf ~/.gradle/caches/ rm -rf ~/.pub-cache/ flutter pub get flutter build apk --verbose ``` ### Level 4: Deep Dive ```bash # Check Flutter setup flutter doctor -v # Verify Java version java -version # Check Gradle dependencies cd android ./gradlew app:dependencies # Build with stacktrace ./gradlew assembleRelease --stacktrace --info # Or with Flutter verbose flutter build apk --verbose --debug ``` ## Build Performance Optimization If builds work but are slow: ### Local Development - Use `android/gradle.properties` - Enable parallel builds: `org.gradle.parallel=true` - Increase workers: `org.gradle.workers.max=4` - More memory: `org.gradle.jvmargs=-Xmx4g` - Enable configuration cache: `org.gradle.configuration-cache=true` ### CI Environment - Use `android/gradle-ci.properties` - Fewer workers: `org.gradle.workers.max=2` - Less memory: `org.gradle.jvmargs=-Xmx3g` - Disable daemon: `org.gradle.daemon=false` - Disable configuration cache: `org.gradle.configuration-cache=false` ## Troubleshooting Checklist - [ ] Run `flutter doctor -v` - all checks pass? - [ ] Java version is 17? (`java -version`) - [ ] Flutter version matches project requirements? - [ ] Run `flutter clean && flutter pub get` - [ ] Try `cd android && ./gradlew clean` - [ ] Check for conflicting dependencies - [ ] Review `pubspec.yaml` for errors - [ ] Verify `android/app/build.gradle.kts` settings - [ ] Check `AndroidManifest.xml` is valid - [ ] Look for file permission issues - [ ] Test on different machine if possible - [ ] Review full error message with `--verbose` - [ ] Check GitHub Issues for similar problems ## Quick Reference Commands ```bash # Clean build flutter clean && flutter pub get && flutter build apk # Verbose build flutter build apk --verbose # Check dependencies flutter pub outdated cd android && ./gradlew app:dependencies # Gradle info cd android && ./gradlew --version ./gradlew tasks --all # Fix common issues dart fix --apply flutter analyze # Update dependencies flutter pub upgrade # Check Flutter setup flutter doctor -v # Test specific build type flutter build apk --debug flutter build apk --profile flutter build apk --release ``` ## When to Seek Help If after trying all solutions the build still fails: 1. **Document the issue**: - Full error message - Build command used - Flutter doctor output - Java version - Steps already tried 2. **Check resources**: - Project's TROUBLESHOOTING.md - Flutter GitHub Issues - Stack Overflow - Plugin's GitHub Issues 3. **Create minimal reproduction**: - Start with `flutter create test_app` - Add dependencies one by one - Identify which dependency causes issue ## Additional Resources - [Flutter Build Modes](https://docs.flutter.dev/testing/build-modes) - [Gradle Performance Guide](https://docs.gradle.org/current/userguide/performance.html) - [Android Build Configuration](https://developer.android.com/studio/build) - Project docs: `BUILD_OPTIMIZATION.md`, `TROUBLESHOOTING.md` --- Source attribution: David-Li0406 Original project: https://github.com/David-Li0406/meta-skill-evloving/blob/ca3a335628981df10c36e00cb9850df2c247ab9a/skill-flow/data/skills-refined-36k/skillsmp/build-fix/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. # Mega AI Hub resource metadata Creator / publisher: David-Li0406 Original project: https://github.com/David-Li0406/meta-skill-evloving/blob/ca3a335628981df10c36e00cb9850df2c247ab9a/skill-flow/data/skills-refined-36k/skillsmp/build-fix/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering Roles: Backend Developer, DevOps / SRE, Mobile Developer Specialties: Backend, Mobile Tools: Flutter, Gradle Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 4f948a9a2ffd3ebb520747786fd84db593995d674013657e8dabaab68ccd0ea0