Omeka has encountered an error

Apache_Solr_HttpTransportException

'400' Status: Bad Request

Apache_Solr_HttpTransportException: '400' Status: Bad Request in /var/www/plugins/SolrSearch/lib/solr-php-client/Service.php:367
Stack trace:
#0 /var/www/plugins/SolrSearch/lib/solr-php-client/Service.php(1224): Apache_Solr_Service->_sendRawGet('http://10.195.4...')
#1 /var/www/themes/default/solr-search/class/functions.php(466): Apache_Solr_Service->search('AND database:"r...', 0, 0, Array)
#2 /var/www/themes/default/solr-search/class/functions.php(553): mySearch(0, 0, false, 'AND database:"r...', 'database', '', Array)
#3 /var/www/themes/default/solr-search/class/functions.php(501): solrConnection('ricercarpicardi...', 1)
#4 /var/www/themes/ricercar/solr-search/results/index.php(219): getResultByName()
#5 /var/www/application/libraries/Omeka/View.php(117): include('/var/www/themes...')
#6 /var/www/application/libraries/Zend/View/Abstract.php(888): Omeka_View->_run('/var/www/themes...')
#7 /var/www/application/libraries/Zend/Controller/Action/Helper/ViewRenderer.php(912): Zend_View_Abstract->render(NULL)
#8 /var/www/application/libraries/Zend/Controller/Action/Helper/ViewRenderer.php(933): Zend_Controller_Action_Helper_ViewRenderer->renderScript('results/index.p...', NULL)
#9 /var/www/application/libraries/Zend/Controller/Action/Helper/ViewRenderer.php(972): Zend_Controller_Action_Helper_ViewRenderer->render()
#10 /var/www/application/libraries/Zend/Controller/Action/HelperBroker.php(277): Zend_Controller_Action_Helper_ViewRenderer->postDispatch()
#11 /var/www/application/libraries/Zend/Controller/Action.php(527): Zend_Controller_Action_HelperBroker->notifyPostDispatch()
#12 /var/www/application/libraries/Zend/Controller/Dispatcher/Standard.php(308): Zend_Controller_Action->dispatch('indexAction')
#13 /var/www/application/libraries/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch(Object(Zend_Controller_Request_Http), Object(Zend_Controller_Response_Http))
#14 /var/www/application/libraries/Zend/Application/Bootstrap/Bootstrap.php(105): Zend_Controller_Front->dispatch()
#15 /var/www/application/libraries/Zend/Application.php(384): Zend_Application_Bootstrap_Bootstrap->run()
#16 /var/www/application/libraries/Omeka/Application.php(79): Zend_Application->run()
#17 /var/www/index.php(24): Omeka_Application->run()
#18 {main}