Unable to serialize session in clustering

since last two days i am performing tomcat clustering. It works fine for a test-app application but when i am passing reference to my webapp, it throws the below exception and clustering does not work. Although members are added successfully but it is unable to serialize the session with the other cluster member.

org.apache.catalina.ha.session.DeltaManager requestCompleted

Unable to serialize delta reques开发者_开发技巧t for sessionid [2045E940A267F15A541F9A4DEBC39F12.tomcatA]

I am using tomcat6.0.18 and hence other member as well. Apache httpd 2.2 in fornt and mod_proxy as a connector between tomcat and apache.

Thanks

Edit:

Found at google -

I think you have something in session which is not serializable. Therefore tomcat aborts writing session contents to file. Next start tomcat tries to load stored sessions, but can't due to previously aborted writing. If you don't care about restart session persistence, you can try to find the proper switch in the conf-docs or just add following to your bin/catalina.sh:

rm -rf work/Catalina/localhost//SESSIONS.ser

Couldn't understand what is this?

There are some classes that saves the session attributes and doesn't implements the serializable interface, i made them serializable and the problem is resolved now. But after then i was caught by another problem. See the link if you can help me enter link description here