Recently, while configuring an Nginx+Tomcat+Memcached cluster for session management, I encountered an error. The approach used the highly efficient Kryo serialization method.
Error message:
Caused by: com.esotericsoftware.kryo.SerializationException: Unable to deserialize object of type: java.util.concurrent.ConcurrentHashMap
I tried many online tutorials, such as registering a new class with Kryo, but the error persisted.
The cause was that the Tomcat lib directory was missing the necessary Wicket JAR files. Upload them as shown below, and it should work:
Attachment Download https://www.cnop.net/uploadfile/2016/1103/20161103090746601.zip