phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('258c871f56d2f3f67c70000a02d8bf6a', -1, 1467353695, 1467353695, '36519490', -10, 0, 0)

Line : 201
File : sessions.php