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 ('2a1c58912448b2c9bb6016db38979b59', -1, 1472155771, 1472155771, '36914620', -1, 0, 0)

Line : 187
File : sessions.php