Something is wrong on your classpath. Either the Solr install was
modified in some way, possible by deleting one or more Lucene jars, or
you have installed an additional copy of one or more Lucene jars
somewhere else where Solr is loading them. It could even be exactly the
same 7.7.1 version as you are running, and could still cause this
problem. Jars like this that are already included in Solr should never
be added to the classpath.