Fixed 2025 : flutter_local_notifications requires core library desugaring to be enabled for app
In a discussion from C's Academy by Jafran Jamal, Neha Singh and Jafran Jamal address a common build error in Flutter: "flutter_local_notifications requires core library desugaring to be enabled for app" This error often appears when adding dependencies like local notifications or upgrading Flutter or Gradle.
Core library desugaring acts as a translation layer, enabling modern Java features (like those from Java 8 or newer, such as java.time package) to run on older Android versions. Without it, applications targeting older APIs (e.g., API 21 or 23) won't understand these newer Java features, leading to build failures. The error messages can be cryptic, sometimes stating "default interface methods are only supported starting with Android N" or "core library desugaring is not enabled".
How to Fix Core Library Desugaring Errors:
The speakers outline a straightforward fix involving changes to the module-level build.gradle file (located in your Flutter project's android directory):
Enable Desugaring: Inside the android block, locate or add the compileOptions block. Set coreLibraryDesugaringEnabled to true.
Set Java Compatibility: Set both sourceCompatibility and targetCompatibility to JavaVersion.VERSION_11.
Add Desugaring Library: In the dependencies block, add the coreLibraryDesugaring dependency with the version com.android.tools:desugar.jdk.libs:2.0.0 (this version is for 2025, and may need to be updated in the future if a newer one is released).
Post-Fix Steps:
After making these changes, perform the following steps to ensure the fix takes effect:
Run flutter clean in your project root to clear old build artifacts.
Run flutter pub get to fetch dependencies.
Rebuild your app using flutter run or by building your APK/app bundle.
Troubleshooting Tips:
If the error persists, try syncing your Gradle files in Android Studio or restarting your IDE.
Double-check your minimum SDK version, as desugaring has limits.
If the error reappears after a major Flutter update, verify if the desugar.jdk.libs version needs to be updated.
Video Chapters with Searchable Keywords:
0:00:00 - Introduction to Core Library Desugaring Error: What is core library desugaring, Flutter build error, Jafran Jamal, Neha Singh, C's Academy.
0:00:22 - When Does the Error Occur? Local notifications, push notifications, Flutter local notifications, upgrading Flutter, Gradle plugin, min-SDK below 26, new dependency.
0:01:55 - How to Spot the Error: Build fails, dependency requires core library desugaring, cryptic error messages, default interface methods, Android N, core library desugaring not enabled.
0:02:45 - Real-World Scenarios: Package update, minor version bump, Java 8 features, compatibility errors, consulting case.
0:03:25 - The Fix: Modifying build.gradle: Module-level build.gradle, compileOptions block, coreLibraryDesugaringEnabled true, JavaVersion.VERSION_11, source compatibility, target compatibility.
0:03:59 - Adding the Desugaring Dependency: Dependencies block, coreLibraryDesugaring, com.android.tools:desugar.jdk.libs:2.0.0, version for 2025.
0:04:26 - Essential Post-Fix Steps: flutter clean, flutter pub get, rebuild app, flutter run, build APK, app bundle.
0:04:51 - Troubleshooting and Further Tips: Sync Gradle files, Android Studio, little elephant icon, restarting IDE, caching issues, mine SDK version, big Flutter update.
0:05:43 - Conclusion and Summary: Bridging compatibility gap, older Android versions, persistent Gradle sync issues, knowing how to handle desugaring