diff --git a/.gitignore b/.gitignore
index 00d9af02..676cf296 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,7 @@ syntax: glob
 !/.idea/codeStyles
 *.iml
 
+.kotlin
 .gradle
 classes
 build/
diff --git a/build-logic/src/main/kotlin/rsocketbuild.multiplatform-base.gradle.kts b/build-logic/src/main/kotlin/rsocketbuild.multiplatform-base.gradle.kts
index 898f147c..671bb288 100644
--- a/build-logic/src/main/kotlin/rsocketbuild.multiplatform-base.gradle.kts
+++ b/build-logic/src/main/kotlin/rsocketbuild.multiplatform-base.gradle.kts
@@ -32,8 +32,10 @@ plugins {
 @OptIn(ExperimentalKotlinGradlePluginApi::class)
 kotlin {
     compilerOptions {
-        // because of https://youtrack.jetbrains.com/issue/KT-64115/KGP-JVM-JS-WASM-The-same-library-can-be-passed-twice-to-the-compiler
-        // allWarningsAsErrors.set(true)
+        // because of INVISIBLE_REFERENCE suppression - will be removed after migration to kotlinx.io
+        if (project.name != "rsocket-test") {
+            allWarningsAsErrors.set(true)
+        }
         progressiveMode.set(true)
         freeCompilerArgs.add("-Xrender-internal-diagnostic-names")
     }
@@ -41,7 +43,10 @@ kotlin {
     sourceSets.configureEach {
         languageSettings {
             if (name.contains("test", ignoreCase = true)) {
+                // for hex API
                 optIn(OptIns.ExperimentalStdlibApi)
+                // for channel.isClosedForSend - need to be replaced by testing via turbine or optIn in place
+                // and GlobalScope - need to be dropped
                 optIn(OptIns.DelicateCoroutinesApi)
 
                 // rsocket related
@@ -54,10 +59,8 @@ kotlin {
     }
 
     targets.withType<KotlinJvmTarget>().configureEach {
-        compilations.configureEach {
-            compilerOptions.configure {
-                freeCompilerArgs.add("-Xjvm-default=all")
-            }
+        compilerOptions {
+            freeCompilerArgs.add("-Xjvm-default=all")
         }
     }
 
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 88f4b12a..a05570bf 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,5 +1,5 @@
 [versions]
-kotlin = "1.9.24"
+kotlin = "2.0.0"
 
 kotlinx-atomicfu = "0.24.0"
 kotlinx-coroutines = "1.8.1"