迁移Android项目至Kotlin 2.0时出现类加载器约束冲突构建错误

问题场景 #

原本运行正常的Android应用，仅修改项目根build.gradle中的Kotlin插件版本：
原配置：

id("org.jetbrains.kotlin.android") version "1.9.20" apply false
id("org.jetbrains.kotlin.jvm") version "1.9.20" apply false

修改为：

id("org.jetbrains.kotlin.android") version "2.0.0" apply false
id("org.jetbrains.kotlin.jvm") version "2.0.0" apply false

Android Studio已将Kotlin编译器版本设为2.0.0，但构建时抛出类加载器约束冲突的LinkageError，核心报错信息如下：

> FAILURE: Build failed with an exception.
> 
> * What went wrong: loader constraint violation in interface itable initialization for class
> com.android.build.gradle.internal.api.VariantFilter: when selecting
> method 'com.android.builder.model.ProductFlavor
> com.android.build.api.variant.VariantFilter.getDefaultConfig()' the
> class loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @4a9dd382 for super interface
> com.android.build.api.variant.VariantFilter, and the class loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @6a9d9b6 of the selected method's class,
> com.android.build.gradle.internal.api.VariantFilter have different
> Class objects for the type com.android.builder.model.ProductFlavor
> used in the signature (com.android.build.api.variant.VariantFilter is
> in unnamed module of loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @4a9dd382, parent loader
> org.gradle.internal.classloader.CachingClassLoader @6916758b;
> com.android.build.gradle.internal.api.VariantFilter is in unnamed
> module of loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @6a9d9b6, parent loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @4a9dd382)
> 
> * Try:
> > Run with --info or --debug option to get more log output.
> > Run with --scan to get full insights.
> > Get more help at https://help.gradle.org.
> 
> * Exception is: java.lang.LinkageError: loader constraint violation in interface itable initialization for class
> com.android.build.gradle.internal.api.VariantFilter: when selecting
> method 'com.android.builder.model.ProductFlavor
> com.android.build.api.variant.VariantFilter.getDefaultConfig()' the
> class loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @4a9dd382 for super interface
> com.android.build.api.variant.VariantFilter, and the class loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @6a9d9b6 of the selected method's class,
> com.android.build.gradle.internal.api.VariantFilter have different
> Class objects for the type com.android.builder.model.ProductFlavor
> used in the signature (com.android.build.api.variant.VariantFilter is
> in unnamed module of loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @4a9dd382, parent loader
> org.gradle.internal.classloader.CachingClassLoader @6916758b;
> com.android.build.gradle.internal.api.VariantFilter is in unnamed
> module of loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @6a9d9b6, parent loader
> org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader
> @4a9dd382)    at
> com.android.build.gradle.internal.VariantManager.<init>(VariantManager.kt:1023)
>   ...（后续类似报错内容省略）

可能的原因 #

• AGP版本与Kotlin 2.0.0不兼容：Kotlin 2.0.0对Android Gradle Plugin（AGP）有最低版本要求，若当前AGP版本过旧，AGP内部的类加载逻辑会与新Kotlin插件产生冲突——不同类加载器加载了com.android.builder.model.ProductFlavor类的不同版本，导致接口方法签名的类实例不统一，触发约束冲突。
• 构建缓存残留：Gradle构建缓存或Android Studio的IDE缓存中保留了旧版本Kotlin、AGP的类文件，新旧类混合加载时，类加载器无法识别为同一类，引发冲突。
• 依赖传递冲突：Kotlin 2.0.0插件可能引入了与当前AGP依赖版本不一致的库，间接导致ProductFlavor等核心类被重复加载。

内容的提问来源于stack exchange，提问作者Tobias Reich