phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('a6fe7dbc00bd3d4fb51320e2b5d48d70', -1, 1414828005, 1414828005, '36577b63', -1, 0, 0)

Line : 187
File : sessions.php