This isn't the full stack trace so it's difficult to be sure, but do
you store AbstractEngineResponses in an HTTP session? If so, it seems
that the class is no longer compatible with the version stored in your
session.
If so, try clearing your cookies. This will create a new session for you.
Fo
http://janrain4j.appspot.com/
javax.servlet.ServletException: java.lang.RuntimeException:
java.io.InvalidClassException:
com.googlecode.janrain4j.api.engage.response.AbstractEngageResponse;
local class incompatible: stream classdesc serialVersionUID =
-8862811237568844288, local class serialVersion
