Firebase performance monitor causing "D8: Unsupported source file type"

I Solve This issue by updating gradle version

classpath 'com.android.tools.build:gradle:3.5.3'

Update: Android Gradle Plugin 3.5.0 fixes this. See this issue and this one issue, both fixed.

(Unfortunately, in my project, this other issue still remains even in 3.5.3.)

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I started getting the same error after updating a (company internal) library dependency, but then I kept getting it even after reverting that update. Very strange!

> Task :app:transformClassesAndResourcesWithR8ForBetaRelease FAILED
R8 is the new Android code shrinker. If you experience any issues, please file a bug at
https://issuetracker.google.com, using 'Shrinker (R8)' as component name. You can
disable R8 by updating gradle.properties with 'android.enableR8=false'.

.../transforms/FirebasePerformancePlugin/beta/release/66/module-info.class:
D8: Unsupported source file type 

The only thing I found that helped was to do what the Gradle build output says and temporarily switch back to ProGuard, with:

android.enableR8=false

in gradle.properties.

This issue was fixed somewhere between Android Studio 3.5 Beta 2 and Android Studio 3.6 Canary 5, there were a bunch of similar issues with module-info.class.

In my case to fix issue I had not only update Android Studio, but also update gradle plugin.

Steps is:

1. Install new version alongside your stable version (You also can configure current version to use updates from canary chanel)

   More info here

   Download link (I downloaded 3.6 Canary 5)

2. After you installed new Android Studio update grade plugin:

   in gradle/wrapper/gradle-wrapper.properties chande distributionUrl to

   distributionUrl=https\://services.gradle.org/distributions/gradle-5.5-all.zip

3. Don't forget Build->Clean Project