AAPT: error: resource android:attr/lStar not found

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

# Which compileSdk is the failing module using?
grep -rn "compileSdk" app/build.gradle* build.gradle*

# Which androidx.core version was resolved, and who asked for it?
./gradlew :app:dependencyInsight --dependency androidx.core:core --configuration debugRuntimeClasspath

# Fix: compile against API 31 or later (targetSdk can stay lower)
# android { compileSdk = 34 }

# In a Flutter or React Native plugin module, the plugin needs the same bump

# Stop dynamic versions resolving to something new without you noticing
grep -rn ":+\"\|:latest" app/build.gradle*

How to diagnose Mobile errors

Mobile build errors are overwhelmingly toolchain and dependency version conflicts rather than code problems. Android builds fail on Gradle, JDK and Android Gradle Plugin version combinations; iOS builds fail on code signing, provisioning profiles and CocoaPods lockfile drift. The productive instinct is to check version compatibility matrices before reading stack traces.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

1. Run the build with full output: ./gradlew assembleDebug --stacktrace --info. Gradle's default output hides the actual failing task.
2. Verify the JDK the build is using (./gradlew -version), not the one on your PATH. Android Gradle Plugin has strict JDK requirements.
3. For CocoaPods, run pod install, not pod update, after pulling changes, and open the .xcworkspace rather than the .xcodeproj.
4. For code signing, check the provisioning profile's expiry, bundle identifier and device list in Xcode's Signing & Capabilities tab before touching certificates.
5. Clear caches only as a last resort and one at a time (./gradlew clean, rm -rf ~/Library/Developer/Xcode/DerivedData, watchman watch-del-all), so you learn which one mattered.

Tools worth reaching for

• ./gradlew --stacktrace --info
• pod install
• xcodebuild -showBuildSettings
• flutter doctor -v
• adb logcat

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

📖 developer.android.com 📖 developer.android.com

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Something missing or wrong?

This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.