Why does the error "[ksp] java.lang.IllegalStateException: unexpected jvm signature V" occur when using Room with KSP and how can I solve it?

I am programming a small Counter app where the count should be stored in a Room database. I am using Kotlin, Jetpack Compose and Room Database with KSP. When I try to run the app the following error occurs: [ksp] java.lang.IllegalStateException: unexpected jvm signature V. When I comment out the code from CounterDatabase.kt the error disappear. Why does it occur and how do I solve it?

My files are:

build.gradle (Project)

plugins { alias(libs.plugins.android.application) apply false alias(libs.plugins.kotlin.compose) apply false // Room id("com.google.devtools.ksp") version "2.3.4" apply false }

build.gradle (Module)

plugins { alias(libs.plugins.android.application) alias(libs.plugins.kotlin.compose) id("com.google.devtools.ksp") } android { namespace = "com.example.counter" compileSdk { version = release(36) { minorApiLevel = 1 } } defaultConfig { applicationId = "com.example.counter" minSdk = 24 targetSdk = 36 versionCode = 1 versionName = "1.0" testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner" } buildTypes { release { isMinifyEnabled = false proguardFiles( getDefaultProguardFile("proguard-android-optimize.txt"), "proguard-rules.pro" ) } } compileOptions { sourceCompatibility = JavaVersion.VERSION_11 targetCompatibility = JavaVersion.VERSION_11 } buildFeatures { compose = true } } dependencies { // Room implementation(libs.androidx.room.runtime) ksp(libs.androidx.room.compiler) implementation(libs.androidx.core.ktx) implementation(libs.androidx.lifecycle.runtime.ktx) implementation(libs.androidx.activity.compose) implementation(platform(libs.androidx.compose.bom)) implementation(libs.androidx.compose.ui) implementation(libs.androidx.compose.ui.graphics) implementation(libs.androidx.compose.ui.tooling.preview) implementation(libs.androidx.compose.material3) implementation(libs.androidx.lifecycle.viewmodel.compose) testImplementation(libs.junit) androidTestImplementation(libs.androidx.junit) androidTestImplementation(libs.androidx.espresso.core) androidTestImplementation(platform(libs.androidx.compose.bom)) androidTestImplementation(libs.androidx.compose.ui.test.junit4) debugImplementation(libs.androidx.compose.ui.tooling) debugImplementation(libs.androidx.compose.ui.test.manifest) }

libs.versions.toml

[versions] agp = "9.2.0" coreKtx = "1.10.1" junit = "4.13.2" junitVersion = "1.1.5" espressoCore = "3.5.1" lifecycleRuntimeKtx = "2.6.1" activityCompose = "1.8.0" kotlin = "2.2.10" composeBom = "2026.02.01" lifecycleViewmodelCompose = "2.10.0" roomCompiler = "2.5.0" roomRuntime = "2.8.4" roomCompilerVersion = "2.8.4" [libraries] androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" } androidx-lifecycle-viewmodel-compose = { module = "androidx.lifecycle:lifecycle-viewmodel-compose", version.ref = "lifecycleViewmodelCompose" } androidx-room-compiler = { module = "androidx.room:room-compiler", version.ref = "roomCompiler" } androidx-room-runtime = { module = "androidx.room:room-runtime", version.ref = "roomRuntime" } junit = { group = "junit", name = "junit", version.ref = "junit" } androidx-junit = { group = "androidx.test.ext", name = "junit", version.ref = "junitVersion" } androidx-espresso-core = { group = "androidx.test.espresso", name = "espresso-core", version.ref = "espressoCore" } androidx-lifecycle-runtime-ktx = { group = "androidx.lifecycle", name = "lifecycle-runtime-ktx", version.ref = "lifecycleRuntimeKtx" } androidx-activity-compose = { group = "androidx.activity", name = "activity-compose", version.ref = "activityCompose" } androidx-compose-bom = { group = "androidx.compose", name = "compose-bom", version.ref = "composeBom" } androidx-compose-ui = { group = "androidx.compose.ui", name = "ui" } androidx-compose-ui-graphics = { group = "androidx.compose.ui", name = "ui-graphics" } androidx-compose-ui-tooling = { group = "androidx.compose.ui", name = "ui-tooling" } androidx-compose-ui-tooling-preview = { group = "androidx.compose.ui", name = "ui-tooling-preview" } androidx-compose-ui-test-manifest = { group = "androidx.compose.ui", name = "ui-test-manifest" } androidx-compose-ui-test-junit4 = { group = "androidx.compose.ui", name = "ui-test-junit4" } androidx-compose-material3 = { group = "androidx.compose.material3", name = "material3" } room-compiler = { group = "androidx.room", name = "room-compiler", version.ref = "roomCompilerVersion" } [plugins] android-application = { id = "com.android.application", version.ref = "agp" } kotlin-compose = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }

CounterDatabase.kt

In this file I do also receive the following two errors:

Function "counterDataAccessObject" is never used

Function "getDatabase" is never used

package com.example.counter.counter.database import android.content.Context import androidx.room.Database import androidx.room.Room import androidx.room.RoomDatabase @Database( entities = [CounterEntity::class], version = 1 ) abstract class CounterDatabase : RoomDatabase() { abstract fun counterDataAccessObject() : CounterDataAccessObject companion object { @Volatile private var INSTANCE: CounterDatabase? = null fun getDatabase(context: Context): CounterDatabase { return INSTANCE ?: synchronized(this) { val instance = Room.databaseBuilder( context.applicationContext, CounterDatabase::class.java, "CounterDatabase" ).build() INSTANCE = instance instance } } } }

Dao file

package com.example.counter.counter.database import androidx.room.Dao import androidx.room.Query @Dao interface CounterDataAccessObject { @Query("SELECT count FROM CounterEntity WHERE id = :id") suspend fun getCount(id: Int): Int? @Query("UPDATE CounterEntity SET count = count + 1 WHERE id = :id") suspend fun incrementCount(id: Int) @Query("UPDATE CounterEntity SET count = count - 1 WHERE id = :id") suspend fun decrementCount(id: Int) }

Entity file

package com.example.counter.counter.database import androidx.room.Entity import androidx.room.PrimaryKey @Entity data class CounterEntity( @PrimaryKey(autoGenerate = true) val id: Int = 0, val count: Int)