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 ('21020b5f090657e4958b1d3d86717b5b', -1, 1711692704, 1711692704, '035c019c', -7, 0, 0)

Line : 187
File : sessions.php