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 ('04b63eb7f3d1c3b2e97d65844f27e3e8', -1, 1539824241, 1539824241, '36a2766b', 5, 0, 0)

Line : 187
File : sessions.php