# Classes up-to-date check: Internal error (java.lang.ClassNotFoundException): kotlin.collections.ArraysKt\_\_\_ArraysJvmKt **URL:** \ **Category:** Uncategorized\ **Created:** [March 8, 2021, 12:18pm UTC](https://discuss.kotlinlang.org/t/classes-up-to-date-check-internal-error-java-lang-classnotfoundexception-kotlin-collections-arrayskt-arraysjvmkt/21130 "2021-03-08T12:18:11Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![pedro.waksman](https://avatars.discourse-cdn.com/v4/letter/p/e0b2c6/32.png) [@pedro.waksman](https://discuss.kotlinlang.org/u/pedro.waksman)\ **Post date:** [March 8, 2021, 12:18pm UTC](https://discuss.kotlinlang.org/t/classes-up-to-date-check-internal-error-java-lang-classnotfoundexception-kotlin-collections-arrayskt-arraysjvmkt/21130/1 "2021-03-08T12:18:11Z")
Getting this error when opening the IntelliJ IDE with any kotlin/maven project. Was working fine until Friday 5 march 2021. After that, the IDE doesn’t even load the project files (source), can’t access any kotlin menu. Windows 10 IntelliJ Ultimate 2020.3.2 Build #IU-203.7148.57 Runtime version: 11.0.9.1+11-b1145.77 amd64 VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o. ![intelliJ error](https://us1.discourse-cdn.com/flex019/uploads/kotlinlang/original/2X/c/cfce8c3d86c5ec8f7b11fa1492cdf4ef949c2d26.png) ``` Internal error (java.lang.ClassNotFoundException): kotlin.collections.ArraysKt___ArraysJvmKt java.lang.ClassNotFoundException: kotlin.collections.ArraysKt___ArraysJvmKt at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:435) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:589) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522) at java.base/java.lang.ClassLoader.defineClass1(Native Method) at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016) at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151) at java.base/java.net.URLClassLoader.defineClass(URLClassLoader.java:514) at java.base/java.net.URLClassLoader$1.run(URLClassLoader.java:422) at java.base/java.net.URLClassLoader$1.run(URLClassLoader.java:416) at java.base/java.security.AccessController.doPrivileged(AccessController.java:691) at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:415) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:589) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522) at java.base/java.lang.ClassLoader.defineClass1(Native Method) at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016) at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151) at java.base/java.net.URLClassLoader.defineClass(URLClassLoader.java:514) at java.base/java.net.URLClassLoader$1.run(URLClassLoader.java:422) at java.base/java.net.URLClassLoader$1.run(URLClassLoader.java:416) at java.base/java.security.AccessController.doPrivileged(AccessController.java:691) at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:415) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:589) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522) at kotlin.collections.CollectionsKt__CollectionsKt.listOf(Collections.kt:77) at org.jetbrains.kotlin.jps.model.KotlinModelSerializerService.getProjectExtensionSerializers(Serializer.kt:23) at org.jetbrains.jps.model.serialization.JpsProjectLoader.loadFromDirectory(JpsProjectLoader.java:149) at org.jetbrains.jps.model.serialization.JpsProjectLoader.loadProject(JpsProjectLoader.java:103) at org.jetbrains.jps.model.serialization.impl.JpsSerializationManagerImpl.loadModel(JpsSerializationManagerImpl.java:24) at org.jetbrains.jps.cmdline.JpsModelLoaderImpl.loadModel(JpsModelLoaderImpl.java:34) at org.jetbrains.jps.cmdline.BuildRunner.load(BuildRunner.java:64) at org.jetbrains.jps.cmdline.BuildSession.runBuild(BuildSession.java:279) at org.jetbrains.jps.cmdline.BuildSession.run(BuildSession.java:132) at org.jetbrains.jps.cmdline.BuildMain$MyMessageHandler.lambda$channelRead0$0(BuildMain.java:219) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) at java.base/java.lang.Thread.run(Thread.java:832) ``` ---
**Author:** ![maksimovicmarko23](https://avatars.discourse-cdn.com/v4/letter/m/7cd45c/32.png) [@maksimovicmarko23](https://discuss.kotlinlang.org/u/maksimovicmarko23)\ **Post date:** [March 8, 2021, 1:12pm UTC](https://discuss.kotlinlang.org/t/classes-up-to-date-check-internal-error-java-lang-classnotfoundexception-kotlin-collections-arrayskt-arraysjvmkt/21130/2 "2021-03-08T13:12:32Z")
I have this same exact Issue, I have noticed that however a file name which is included in this stack trace is blocked by my anti virus. Are you using bit defender by chance? ---
**Author:** ![pedro.waksman](https://avatars.discourse-cdn.com/v4/letter/p/e0b2c6/32.png) [@pedro.waksman](https://discuss.kotlinlang.org/u/pedro.waksman)\ **Post date:** [March 8, 2021, 1:18pm UTC](https://discuss.kotlinlang.org/t/classes-up-to-date-check-internal-error-java-lang-classnotfoundexception-kotlin-collections-arrayskt-arraysjvmkt/21130/3 "2021-03-08T13:18:09Z")
Yap, I’m, don’t tell me that it is blocking the IDE project! dang it… ![ArraysKt ____](https://us1.discourse-cdn.com/flex019/uploads/kotlinlang/original/2X/a/af0f9469a90fab65eaab9ca8ed189bd228ca513e.png) ---
**Author:** ![pedro.waksman](https://avatars.discourse-cdn.com/v4/letter/p/e0b2c6/32.png) [@pedro.waksman](https://discuss.kotlinlang.org/u/pedro.waksman)\ **Post date:** [March 8, 2021, 2:42pm UTC](https://discuss.kotlinlang.org/t/classes-up-to-date-check-internal-error-java-lang-classnotfoundexception-kotlin-collections-arrayskt-arraysjvmkt/21130/4 "2021-03-08T14:42:46Z")
What I did to get around this, I have uninstalled the IDE, cache and config. Reinstalled, open the ide for the “first time”, in plugin, selected kotlin and delete/unistall. Restart. dowloaded the kotlin 1.20 from the kotlin website, installed the plugin from the disk. Now it says it is 1.30 instead of 1.20 but it is running and compiling everything. I have this ticket at the IntelliJ bug tracker: [https://youtrack.jetbrains.com/issue/KTIJ-3770](https://youtrack.jetbrains.com/issue/KTIJ-3770) Other people seens to have same issue with other plugins