"Minimum supported Gradle version is 4.4" error started today; no code changes

Question

Today, multiple developers on my team started seeing this error when they attempt to run any Gradle task.

* Where:
Build file 'C:\dev\src\my_app_name\app\build.gradle' line: 1

* What went wrong:
A problem occurred evaluating project ':app'.
> Failed to apply plugin [id 'com.android.application']
   > Minimum supported Gradle version is 4.4. Current version is 4.1. If using the gradle wrapper, try editing the distributionUrl in C:\dev\src\my_app_name\gradle\wrapper\gradle-wrapper.properties to gradle-4.4-all.zip

Absolutely no code or config changes were made; Gradle builds just suddenly started to fail. Anyone know why this would happen? My best guess is that a plugin with a dependency on a specific version of Gradle auto-updated itself, but I'm not sure how to figure out which one it is. The line number would suggest that it was the com.application.plugin plugin itself.

I am aware that Android Studio updates often require a corresponding upgrade to Gradle, but nobody on my team updated Android Studio. And, according to the Android-Studio-Gradle version compatibility table, Gradle 4.1 should still work fine with Android Studio 3.0.1, which is what I have been running for some time.

We recently started using Kotlin, and I thought that might be part of the problem, but completely removing everything related to Kotlin didn't help.

I have tried deleting the Gradle caches/ directory, running ./gradlew cleanBuildCache, deleting our project's build/ directories, killing Gradle daemons via ./gradlew --stop, and rebooting -- all to no avail.

I also tried upgrading to Gradle 4.4, but that resulted in a "CIRCULAR REFERENCE" NullPointerException error during DexMergerTransform (separate issue), for reasons that are entirely unclear to me. I'd like to be able to force my environment to NOT take on a Gradle 4.4 dependency right now... but I don't know what suddenly triggered this dependency.

Answer 1

The problem turned out to be that we were using a non-specific version of a plugin. When a change was made to the plugin, the new version was downloaded to our dev environments, and it introduced a dependency on a version of Gradle higher than the one we were using.

In our case, this was the culprit:

classpath 'com.jakewharton:butterknife-gradle-plugin:9.0.0-SNAPSHOT'

Downgrading to version 8.5.1 of the Butterknife plugin eliminated the dependency on Gradle 4.4.

You also have the option of linking to a specific pre-release "nightly" version. However, this is less than ideal, since these bits don't remain available for long, and you might want to download a build and keep it in your local lib. For example:

classpath 'com.jakewharton:butterknife-gradle-plugin:9.0.0-20180727.012508-40'

Answer 2

instead of down-grading, one could provide the plugin in version 9.0.0 with the expect version of Gradle, by editing the file gradle/wrapper/gradle-wrapper.properties; for example:

distributionUrl=https\://services.gradle.org/distributions/gradle-4.5-all.zip

version 4.5 works stable and might not create the circular reference, alike 4.4 does. and when looking at the issues tracker on GitHub, this Gradle plugin might add more problems, than it would serve any real purpose - because the Android SDK already supports two-way data-binding.

currently the artifacts still list 8.8.1 as the latest version; while a SNAPSHOT is barely stable... that nothing happend there since over a year, hints for that this project might have been abandoned... most likely because of Architecture Components data-binding.