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 ('708014712f9f59f1a3ba6ff0d1fb6773', -1, 1711649910, 1711649910, '343737ef', -7, 0, 0)

Line : 187
File : sessions.php