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 ('1e497d957a9cfa0f9b77927831347894', -1, 1409640368, 1409640368, '365ab04f', 20, 0)

Line : 315
File : sessions.php