phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('0e0347a023d8c637655d57432a8d09e5', -1, 1417241466, 1417241466, '36ea07a1', 4, 0, 0)

Line : 187
File : sessions.php