I’m having this issue:

e: java.lang.IncompatibleClassChangeError: Found interface org.jetbrains.kotlin.ir.declarations.IrClass, but class was expected

at androidx.compose.compiler.plugins.kotlin.VersionChecker.check(VersionChecker.kt:65)

at androidx.compose.compiler.plugins.kotlin.ComposeIrGenerationExtension.generate(ComposeIrGenerationExtension.kt:49)

at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade$doGenerateFiles$1.invoke(JvmBackendFacade.kt:72)

at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade$doGenerateFiles$1.invoke(JvmBackendFacade.kt:34)

at org.jetbrains.kotlin.psi2ir.Psi2IrTranslator.generateModuleFragment(Psi2IrTranslator.kt:98)

at org.jetbrains.kotlin.backend.jvm.JvmBackendFacade.doGenerateFiles(JvmBackendFacade.kt:87)

at org.jetbrains.kotlin.backend.jvm.JvmIrCodegenFactory.generateModule(JvmIrCodegenFactory.kt:40)

at org.jetbrains.kotlin.codegen.KotlinCodegenFacade.compileCorrectFiles(KotlinCodegenFacade.java:35)

at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.generate(KotlinToJVMBytecodeCompiler.kt:616)

at org.jetbrains.kotlin.cli.jvm.compiler.KotlinToJVMBytecodeCompiler.compileModules$cli(KotlinToJVMBytecodeCompiler.kt:203)

at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:164)

at org.jetbrains.kotlin.cli.jvm.K2JVMCompiler.doExecute(K2JVMCompiler.kt:51)

at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:86)

at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:44)

at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:98)

at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:346)

at org.jetbrains.kotlin.incremental.IncrementalJvmCompilerRunner.runCompiler(IncrementalJvmCompilerRunner.kt:102)

at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compileIncrementally(IncrementalCompilerRunner.kt:240)

at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.access$compileIncrementally(IncrementalCompilerRunner.kt:39)

at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner$compile$2.invoke(IncrementalCompilerRunner.kt:81)

at org.jetbrains.kotlin.incremental.IncrementalCompilerRunner.compile(IncrementalCompilerRunner.kt:93)

at org.jetbrains.kotlin.daemon.CompileServiceImplBase.execIncrementalCompiler(CompileServiceImpl.kt:601)

at org.jetbrains.kotlin.daemon.CompileServiceImplBase.access$execIncrementalCompiler(CompileServiceImpl.kt:93)

at org.jetbrains.kotlin.daemon.CompileServiceImpl.compile(CompileServiceImpl.kt:1633)

at jdk.internal.reflect.GeneratedMethodAccessor99.invoke(Unknown Source)

at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.base/java.lang.reflect.Method.invoke(Method.java:566)

at java.rmi/sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:359)

at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:200)

at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:197)

at java.base/java.security.AccessController.doPrivileged(Native Method)

at java.rmi/sun.rmi.transport.Transport.serviceCall(Transport.java:196)

at java.rmi/sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:562)

at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:796)

at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:677)

at java.base/java.security.AccessController.doPrivileged(Native Method)

at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:676)

at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)

at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)

at java.base/java.lang.Thread.run(Thread.java:834)

e: java.lang.IncompatibleClassChangeError: Found interface org.jetbrains.kotlin.ir.declarations.IrClass, but class was expected

Execution failed for task ':app:compileDebugKotlin'.

> Internal compiler error. See log for more details

are you using kotlin 1.4.20?

https://kotlinlang.slack.com/archives/CJLTWPH7S/p1606933913014500 Take a look , change kotlin compiler version accordingly

@Alexjlockwood yes I'm using Kotlin 1.4.20