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) VALUES ('7c1bc277967fefb4afd8daee801e5f58', -1, 1397862937, 1397862937, '36cdec2e', 14, 0)

Line : 158
File : sessions.php