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, session_admin) VALUES ('02df00d6dab0b7bec951f7a3520efb9b', -1, 1414046052, 1414046052, 'ae814aba', 30, 0, 0)

Line : 187
File : sessions.php