phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO r2ok_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('b70a03ce24f53efe8df25ed8bd0a9c0e', -1, 1524226981, 1524226981, '36506778', -9, 0, 0)

Line : 187
File : sessions.php