Solving Gradle & Kotlin Version Conflicts in Flutter Project

Gradle & Kotlin version conflicts in Flutter project can quickly turn a simple build into a frustrating debugging marathon.
If your Flutter Android build keeps failing despite correct configuration, this guide explains why it happens and how to fix it reliably.

Flutter provides a strong ecosystem for cross-platform development, but the Android build toolchain (Gradle, Kotlin, Android Gradle Plugin) can sometimes become unstable when local environments fall out of sync with project configuration. This article outlines a practical, reliable approach to diagnosing and fixing persistent Gradle and Kotlin version conflicts.

Problem

After cloning a Flutter project, the Android build repeatedly failed despite updating:

• App-level build.gradle

• Project-level build.gradle

Additional symptoms included:

• Gradle continuously downloading dependencies without resolving errors

• The global .gradle directory growing abnormally large

• Version changes not being reflected in build behavior

In one case, the .gradle folder reached up to 24 GB, clearly indicating excessive caching and conflicting artifacts.

Why This Happens

This issue typically stems from a combination of tooling and environment problems rather than project code.

1. Tooling version mismatch

Gradle builds depend on tight compatibility between:

• Android Gradle Plugin (AGP)

• Kotlin Gradle Plugin

• Gradle Wrapper

• Android Studio version

If these are misaligned, builds can fail even if configuration files appear correct.

2. Outdated configuration in settings.gradle

Modern Flutter and Android projects often define plugin versions inside settings.gradle.

Updating only build.gradle files while leaving outdated versions in settings.gradle can cause the build system to continue resolving incompatible plugins.

3. Corrupted or bloated Gradle cache

Gradle stores dependencies, compiled artifacts, and metadata inside:

C:\Users\<username>\.gradle

Over time — especially when working across multiple projects with different tooling versions — this cache can become:

• Excessively large

• Internally inconsistent

• Partially corrupted

When this happens, Gradle may continue using outdated artifacts even after configuration changes.

A Reliable Debugging Strategy: The Dummy Project Method

Instead of guessing compatible versions, a more reliable approach is:

1. Create a new, empty Flutter project in Android Studio

2. Allow it to sync successfully

3. Observe the versions used for:

   • Gradle

   • Kotlin

   • Android Gradle Plugin

These versions represent what your installed Android Studio natively supports.

They can then be safely applied to the real project across:

• settings.gradle

• Root build.gradle

• App-level build.gradle

• gradle-wrapper.properties

The Often Missed File: settings.gradle

Many developers update only build.gradle, but forget that plugin versions are often defined inside settings.gradle.

Example configuration:

pluginManagement {
def flutterSdkPath = {
def properties = new Properties()
file(“local.properties”).withInputStream { properties.load(it) }
def flutterSdkPath = properties.getProperty(“flutter.sdk”)
assert flutterSdkPath != null, “flutter.sdk not set in local.properties”
return flutterSdkPath
}

settings.includeBuild(“${flutterSdkPath()}/packages/flutter_tools/gradle”)

repositories {
google()
mavenCentral()
gradlePluginPortal()
}

plugins {
// These versions must match the working Dummy Project
id “dev.flutter.flutter-gradle-plugin” version “1.0.0” apply false
id “org.jetbrains.kotlin.android” version “1.9.0” apply false
}
}

If this file still references older versions, conflicts will persist even when the rest of the project is updated.

Final Resolution

Even after aligning all configuration files, the issue persisted due to the corrupted local environment. The final and effective fix was:

1. Delete the global Gradle cache:

C:\Users\<YourUser>\.gradle

2. Run a clean rebuild:

flutter clean
flutter pub get
flutter build

This forced Gradle to re-download only the correct, compatible artifacts.

Result:

• Builds stabilized

• Version changes began working as expected

• Dependency downloads normalized

• Cache size returned to reasonable levels

Key Takeaway

When build errors persist despite correct configuration:

• The problem may lie in the local development environment, not the project code.

• flutter clean is often insufficient for deeply corrupted Gradle caches.

• A bloated .gradle directory is a strong signal that a full cache reset may be required.

Maintaining a clean and consistent build environment is just as important as correct dependency configuration.

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