🐞Android plugin not found when using AGP9

[EdwynZN]

• I have read the README
• I have done the setup for Android
• I have done the setup for iOS
• I have ran the sample app and it does not work there

Version

Technology	Version
Workmanager version	0.10.1
Xcode version	26.2
Swift version	6.2.3
iOS deployment target	15

Describe the error

Caused by: org.gradle.api.internal.tasks.compile.CompilationFailedException: Compilation failed; see the compiler output below.
  Error: [        ] /home/runner/work/mobile-app/mobile-app/android/app/src/main/java/io/flutter/plugins/GeneratedPluginRegistrant.java:164: error: cannot find symbol
  [        ]       flutterEngine.getPlugins().add(new dev.fluttercommunity.workmanager.WorkmanagerPlugin());
  [        ]                                                                          ^
  [        ]   symbol:   class WorkmanagerPlugin
  [        ]   location: package dev.fluttercommunity.workmanager

I believe this has to be with gradle and AGP version as other projects with workmanager runs normally. I tested it in my computer and with CI/CD but fails only in android. I dont have a reproducible project right now but it seems that when upgrading from 0.9.0+3 to 0.10.1 the error appears, I had to downgrade and clear the transitive packages upgraded

plugins {
    id("dev.flutter.flutter-plugin-loader") version "1.0.0"
    id("com.android.application") version "9.2.1" apply false
    // START: FlutterFire Configuration
    id("com.google.gms.google-services") version("4.4.4") apply false
    id("com.google.firebase.firebase-perf") version("2.0.2") apply false
    id("com.google.firebase.crashlytics") version("3.0.7") apply false
    // END: FlutterFire Configuration
    id("org.jetbrains.kotlin.android") version "2.3.10" apply false
}

and in gradle-wrapper.properties:

distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-9.5.1-all.zip

Output of flutter doctor -v

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.44.0, on macOS 26.5.2 25F84 darwin-arm64, locale en-MX)
[✓] Android toolchain - develop for Android devices (Android SDK version 36.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 26.2)
[✗] Chrome - develop for the web (Cannot find Chrome executable at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome)
    ! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.
[✓] Connected device (1 available)
    ! Error: Browsing on the local area network for Edwin’s iPhone. Ensure the device is unlocked and attached with a cable or associated
      with the same local area network as this Mac.
      The device must be opted into Developer Mode to connect wirelessly. (code -27)
[✓] Network resources

[ened]

Thanks for the detailed report. I reproduced this exactly (Flutter 3.44.0, AGP 9.x, android.builtInKotlin=false): cannot find symbol: class WorkmanagerPlugin.

Root cause: it's not the plugin — it's AGP 9 + the legacy Kotlin mode. On AGP 9, Kotlin compilation moved to AGP's built-in Kotlin, and applying the Kotlin Gradle Plugin to a library module is a no-op (no compileDebugKotlin task gets registered). Flutter 3.44 templates default to android.builtInKotlin=false (legacy mode), which disables built-in Kotlin entirely — so any plugin with Kotlin sources (firebase, shared_preferences, ...) fails to compile its classes, and GeneratedPluginRegistrant can't find them. I verified this matrix:

Config	Result
AGP 9.x + android.builtInKotlin=true (or unset)	✅ builds
AGP 9.x + android.builtInKotlin=false	❌ cannot find symbol (KGP applied or not)

Fix (app-side): remove android.builtInKotlin=false and android.newDsl=false from android/gradle.properties and migrate to built-in Kotlin — Flutter prints exactly this guidance on build, and the migration guide is at https://docs.flutter.dev/release/breaking-changes/migrate-to-built-in-kotlin/for-app-developers

Plugin-side: I opened #711 which aligns the plugin with Flutter's built-in Kotlin guide (kotlin.compilerOptions instead of the removed android.kotlinOptions), verified against AGP 9.0.1 and 9.2.1.

Closing as not-a-bug (works after the app migration).

[EdwynZN]

I'll just reopen it so you can check if #721 actually solves the problem for all cases (<AGP9, >=AGP9 with and without android.builtInKotlin=false).

I tested it and my project failed failed with the current ^0.10.5 but runs with the latest version using the forked branch.