Got this while rebuilding indexes after an import. It seems to have hit a post with a in it.
Invalid bind-variable name ''
[*]Zend_Db_Statement->_parseParameters() in Zend/Db/Statement.php at line 114
[*]Zend_Db_Statement->__construct() in Zend/Db/Adapter/Mysqli.php at line 381
[*]Zend_Db_Adapter_Mysqli->prepare() in Zend/Db/Adapter/Abstract.php at line 478
[*]Zend_Db_Adapter_Abstract->query() in XenForo/Search/SourceHandler/MySqlFt.php at line 117
[*]XenForo_Search_SourceHandler_MySqlFt->_pushToIndex() in XenForo/Search/SourceHandler/MySqlFt.php at line 65
[*]XenForo_Search_SourceHandler_MySqlFt->insertIntoIndex() in XenForo/Search/Indexer.php at line 44
[*]XenForo_Search_Indexer->insertIntoIndex() in XenForo/Search/DataHandler/Post.php at line 47
[*]XenForo_Search_DataHandler_Post->_insertIntoIndex() in XenForo/Search/DataHandler/Abstract.php at line 227
[*]XenForo_Search_DataHandler_Abstract->insertIntoIndex() in XenForo/Search/DataHandler/Post.php at line 119
[*]XenForo_Search_DataHandler_Post->quickIndex() in XenForo/Search/DataHandler/Post.php at line 89
[*]XenForo_Search_DataHandler_Post->rebuildIndex() in XenForo/CacheRebuilder/SearchIndex.php at line 83
[*]XenForo_CacheRebuilder_SearchIndex->rebuild() in XenForo/ControllerHelper/CacheRebuild.php at line 26
[*]XenForo_ControllerHelper_CacheRebuild->rebuildCache() in XenForo/ControllerAdmin/Tools.php at line 63
[*]XenForo_ControllerAdmin_Tools->actionCacheRebuild() in XenForo/FrontController.php at line 310
[*]XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 132
[*]XenForo_FrontController->run() in /var/www/.../admin.php at line 13