I've seen that before on a 3.1 check out after i compiled the clustering component, copied the jars and started Solr. For some reason , recompiling didn't work and doing an ant clean in front didn't fix it either. Updating to a revision i knew did work also failed.
I just removed the entire checkout and took it back in, repeated my steps and it works fine now. > help me out of this error: > > java.lang.NoClassDefFoundError: org/apache/solr/util/plugin/SolrCoreAware
