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Android build failed for kotlin with ksp

Unable to load class &#39;com.google.devtools.ksp.impl.KotlinSymbolProcessing$ExitCode&#39;
com.google.devtools.ksp.impl.KotlinSymbolProcessing$ExitCode

Dependencies
classpath &#39;org.jetbrains.kotlin:kotlin-gradle-plugin:2.3.10&#39;

plugins
id &#39;org.jetbrains.kotlin.android&#39; version &#39;2.3.10&#39; apply false
id &#39;com.google.devtools.ksp&#39; version &#39;2.3.10&#39; apply false

More error log

class com.android.build.gradle.internal.dsl.ApplicationExtensionImpl$AgpDecorated_Decorated cannot be cast to class com.android.build.gradle.BaseExtension (com.android.build.gradle.internal.dsl.ApplicationExtensionImpl$AgpDecorated_Decorated and com.android.build.gradle.BaseExtension are in unnamed module of loader org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader @4584c85a)
class com.android.build.gradle.internal.dsl.ApplicationExtensionImpl$AgpDecorated_Decorated cannot be cast to class com.android.build.gradle.BaseExtension (com.android.build.gradle.internal.dsl.ApplicationExtensionImpl$AgpDecorated_Decorated and com.android.build.gradle.BaseExtension are in unnamed module of loader org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader @4584c85a)
Gradle&#39;s dependency cache may be corrupt (this sometimes occurs after a network connection timeout.)

Tried different version of combination for kotlin-android and ksp all of them are failed, even tried with below code but facing same error

plugins
id &#39;org.jetbrains.kotlin.android&#39; version &#39;2.4.10&#39; apply false
id &#39;com.google.devtools.ksp&#39; version &#39;2.3.11&#39; apply false

Already tried invalidate cache and restart IDE.

Gradle version 9.7.0 
AGP vervsion 9.3.1 
Android studio Quail 3, 2026.1.3 Patch 1

Aug 12 at 8:10 AM

Pratik

#android #kotlin #build #ksp

Accepted Answer

This is a known compatibility issue between KSP and the Kotlin Gradle plugin versions. They must match exactly.

With Kotlin 2.3.10 you need KSP 2.3.10-1.0.x — the first part of the KSP version must match your Kotlin version exactly.

Fix your plugins block like this:

kotlin

plugins {
    id &#39;org.jetbrains.kotlin.android&#39; version &#39;2.3.10&#39; apply false
    id &#39;com.google.devtools.ksp&#39; version &#39;2.3.10-1.0.25&#39; apply false
}

The KSP version format is always <kotlin-version>-<ksp-version>. You cannot mix 2.3.10 Kotlin with 2.3.11 KSP — they must start with the same Kotlin version number.

Also try these steps in order:

Update your build.gradle with the matching versions above
Delete .gradle folder in your project root
Run ./gradlew clean in terminal
Sync project again

You can always check the correct matching version at: github.com/google/ksp/releases

Ramzan

Aug 12 at 11:44 AM

Dependencies classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:2.3.10' plugins id 'org.jetbrains.kotlin.android' version '2.3.10' apply false id 'com.google.devtools.ksp' version '2.3.10' apply false

class com.android.build.gradle.internal.dsl.ApplicationExtensionImpl$AgpDecorated_Decorated cannot be cast to class com.android.build.gradle.BaseExtension (com.android.build.gradle.internal.dsl.ApplicationExtensionImpl$AgpDecorated_Decorated and com.android.build.gradle.BaseExtension are in unnamed module of loader org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader @4584c85a) class com.android.build.gradle.internal.dsl.ApplicationExtensionImpl$AgpDecorated_Decorated cannot be cast to class com.android.build.gradle.BaseExtension (com.android.build.gradle.internal.dsl.ApplicationExtensionImpl$AgpDecorated_Decorated and com.android.build.gradle.BaseExtension are in unnamed module of loader org.gradle.internal.classloader.VisitableURLClassLoader$InstrumentingVisitableURLClassLoader @4584c85a) Gradle's dependency cache may be corrupt (this sometimes occurs after a network connection timeout.)