Looks like Solarium hardcodes a default header "Content-Type: text/xml; charset=utf-8" if none provided. Removing it solves the problem.
It seems that Solr 5.1 doesn't support this content-type. -- View this message in context: http://lucene.472066.n3.nabble.com/Bad-contentType-for-search-handler-text-xml-charset-UTF-8-tp4200314p4201579.html Sent from the Solr - User mailing list archive at Nabble.com.
