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 ('f858d577a2ad4892d4921f02412faac9', -1, 1397862931, 1397862931, '36cdec2e', 2, 0)

Line : 158
File : sessions.php