Martin Zeitler

Software Developer

Pragmatic programmer and automation geek. Highly experienced Stack Overflow contributor with numerous gold badges.

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Mobile Dev Fix Kotlin Unit Error Metadata 2.1.0 vs Compiler 1.9.0 in Android Studio

Resolve 'kotlin.Unit' incompatible version error in Kotlin Android Studio after adding Firebase Cloud Messaging Java service. Upgrade Kotlin to 2.1.20, align Gradle, AGP, Java 17 for firebase messaging compatibility.

#android
#android-studio
#firebase
#gradle
#kotlin

3 answers• 1 view

02/27/2026, 05:30 PM