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 ('2b1b741659d999d2fd6410bd87c1a35c', -1, 1506357869, 1506357869, '3651585d', -4, 0, 0)

Line : 187
File : sessions.php