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 ('5784cbc14a1a410afbb1730c67e09bb9', -1, 1406754843, 1406754843, '36e2bc8e', 1, 0)

Line : 315
File : sessions.php