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 ('b4d4b230aa882b66e3d6b0d61e39ae05', -1, 1529322277, 1529322277, '36c69e18', 46, 0, 0)

Line : 187
File : sessions.php