phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('6d21a3a0ca1926cf626231c43ed86e9b', -1, 1490228268, 1490228268, '369eb7bc', -9, 0, 0)

Line : 187
File : sessions.php