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 ('ae36f4a8123cd5b630d69bc89c70e607', -1, 1539947295, 1539947295, '36e11a2c', 6, 0, 0)

Line : 187
File : sessions.php