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You might've forgot to add a dependency or it's written wrong. Also, you might be using incompatible versions of Java and Hibernate. More on this here:


A few things cause this exception: 1) Check if you have all jars and if they're in the correct path when running. 2) Your classpath might be broken, you can define it in the command line with "java -cp yourClassPath" or at your IDE if you're using one.


Needs to add netty-transport-native-epoll with a OS classifier to the classpath, it's not included in netty-all


This might be an issue with the file location in the Spark submit command. Try it with "spark-submit --master spark://master:7077 {file location}"

You have a different solution? A short tip here would help you and many other users who saw this issue last week.

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  • New Issue
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    • java.lang.NoClassDefFoundError: io
    • etty/buffer/ByteBufOutputStream at java.lang.Class.getDeclaredFields0(Native Method) at java.lang.Class.privateGetDeclaredFields(Unknown Source) at java.lang.Class.getDeclaredFields(Unknown Source) at amidst.mojangapi.minecraftinterface.RecognisedVersion.getMainClassFields( at amidst.mojangapi.minecraftinterface.RecognisedVersion.generateMagicString( at amidst.mojangapi.minecraftinterface.RecognisedVersion.from( at amidst.mojangapi.minecraftinterface.local.LocalMinecraftInterfaceBuilder.create( at at amidst.mojangapi.MojangApi.set( at amidst.gui.profileselect.LocalProfileComponent.tryLoad( at amidst.threading.WorkerExecutor.lambda$run$11( at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$ Source) at Source) Caused by: java.lang.ClassNotFoundException: io.netty.buffer.ByteBufOutputStream at Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) ... 14 more

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