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 ('111b2d89e19d7524b75b21eb6c8c5954', -1, 1768304860, 1768304860, 'd849d81a', 12, 0, 0)

Line : 187
File : sessions.php