An upgrade to a clustered liferay portal failed to work and just dumped this error to the logs:
java.lang.NoSuchMethodError: net.sf.ehcache.util.ClassLoaderUtil.getStandardClassLoaderIt did not work right until I upgraded ehcache-jgroupsreplication.jar to deal with EHC-1116 . I don't think the patch is in the recent ehcache releases yet (it's not in the release notes for 2.10.1 or 2.8.8), but just building the trunk of the jgroupsreplication subproject worked for me. That subproject code seems very stable anyways. That patch which just went in in February 2016 was the only change since 2014. Not very risky and with Maven it ran the unit tests when it built anyways.