Looks like one of my users uploaded an image with Cyrillic characters in the filename. W3TC is now throwing DB errors like this:
WordPress database error Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation '=' for query SELECT remote_path FROM b2c_w3tc_cdn_queue WHERE remote_path = 'wp-content/uploads/2014/04/Снимок-экрана-2014-04-22-в-13.20.50.png' made by shutdown_action_hook, do_action('shutdown'), call_user_func_array, wp_ob_end_flush_all, ob_end_flush, W3_Plugin_TotalCache->ob_callback, w3tc_do_ob_callbacks, call_user_func, W3_Plugin_Cdn->ob_callback, preg_replace_callback, W3_Plugin_Cdn->link_replace_callback, W3_Plugin_Cdn->_link_replace_callback_checks, W3_Db->query, W3_DbCache->query, W3_DbCallUnderlying->query, W3_Db->query, W3_DbProcessor->query, W3_Db->default_query
Any ideas??