runRun this query
UPDATE core_config_data set value = 'mysql' where path='catalog/search/engine';
UPDATE core_config_data set value = 'mysql' where path='catalog/search/engine';
andAnd run theseFollowing commands
php -f bin/magento setup:upgrade php -f bin/magento cache:flush php -f bin/magento indexer:reindex
php -f bin/magento setup:upgrade
php -f bin/magento cache:flush
php -f bin/magento indexer:reindex