PHP >= 5.2.0 (or older with JSON PECL extension or other json_decode function implementation). Solr >= 1.2 Since I'm unable to currently update the Solr WIKI page that points to this issue and its downloads, I've left this issue open. I, however, need to note that active releases of the PHP code are now available from: http://code.google.com/p/solr-php-client/downloads/list If you have any issues