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 ('15e29d9917067aecc82274fd48a61333', -1, 1524205587, 1524205587, '3650082c', 36, 0, 0)

Line : 187
File : sessions.php