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 ('038d2bf4d06e8b4940f94786903aea02', -1, 1537760119, 1537760119, '36c68e79', 0, 0, 0)

Line : 187
File : sessions.php