org.apache.solr.common.SolrException: missing content stream

/solr/update will look for any input documents to be indexed. Running plain /solr/update will cause this exception since there is no input for it. The easiest way to run it is like,

java -Durl=localhost:8080/<your apache solr context path, mostly solr>/update -jar post.jar *.xml

This can also happen through SolrJ/spring-data-solr if you try to persist an empty collection of documents.

So solrClient.add(new ArrayList<SolrInputDocument>(), 10000);

would also cause the error.

If you add commit parameter i.e. ?commit=true, it will work