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 ('f921c86fd4ce6af8eb0b8f44359610e0', -1, 1414192110, 1414192110, '36ea4a55', 11, 0)

Line : 315
File : sessions.php