Omeka has encountered an error

Apache_Solr_HttpTransportException

'400' Status: Bad Request

Apache_Solr_HttpTransportException: '400' Status: Bad Request in /home/www/plugins/SolrSearch/lib/solr-php-client/Service.php:338
Stack trace:
#0 /home/www/plugins/SolrSearch/lib/solr-php-client/Service.php(1176): Apache_Solr_Service->_sendRawGet()
#1 /home/www/plugins/SolrSearch/controllers/ResultsController.php(219): Apache_Solr_Service->search()
#2 /home/www/plugins/SolrSearch/controllers/ResultsController.php(68): SolrSearch_ResultsController->_search()
#3 /home/www/application/libraries/Zend/Controller/Action.php(516): SolrSearch_ResultsController->indexAction()
#4 /home/www/application/libraries/Zend/Controller/Dispatcher/Standard.php(308): Zend_Controller_Action->dispatch()
#5 /home/www/application/libraries/Zend/Controller/Front.php(954): Zend_Controller_Dispatcher_Standard->dispatch()
#6 /home/www/application/libraries/Zend/Application/Bootstrap/Bootstrap.php(105): Zend_Controller_Front->dispatch()
#7 /home/www/application/libraries/Zend/Application.php(384): Zend_Application_Bootstrap_Bootstrap->run()
#8 /home/www/application/libraries/Omeka/Application.php(73): Zend_Application->run()
#9 /home/www/index.php(49): Omeka_Application->run()
#10 {main}