Error!

MySQL Error: Incorrect integer value: '' for column 'ref_id' at row 1
SQL Statement: INSERT INTO user_tracking_current_9 (object_type,object_id,req_url,http_referer,accessed_on,user_id,ref_type,ref_id,user_ip,user_agent) VALUES ('content','305453','buyersguide/profile/probst-class-gmbh-co-kg','','2022-01-22 08:29:31',-1,'','','3.81.172.77','CCBot/2.0 (https://commoncrawl.org/faq/)')