Recently, while configuring an nginx+tomcat+memcached cluster for session management, I encountered an error. The method used was the relatively efficient kryo approach.
Error message:
Caused by: com.esotericsoftware.kryo.SerializationException: Unable to deserialize object of type: java.util.concurrent.ConcurrentHashMap
I tried many tutorials online, such as registering a new class with kryo, but the error persisted.
The cause was that the necessary wicket jar files were missing from the lib directory under tomcat. Upload them as shown below, and it will work:
Attachment download https://www.cnop.net/uploadfile/2016/1103/20161103090746601.zip