phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('9dfe38523fa22405b0ef6cfdd8d62a81', -1, 1540170897, 1540170897, '369c27f5', 10, 0, 0)

Line : 187
File : sessions.php