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 ('6d87cfa324f2b4388cdc9b8e3cf71e32', -1, 1506203563, 1506203563, '36510849', -11, 0, 0)

Line : 187
File : sessions.php