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 ('d7419d6b3cf5a6fa1a66a0ce573537bf', -1, 1397941112, 1397941112, '36f25559', 4, 0)

Line : 158
File : sessions.php