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 ('4fbe2f8b8400aaa2512bc6e8c737ac1f', -1, 1524207033, 1524207033, '3650082c', 5, 0, 0)

Line : 187
File : sessions.php