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 ('53fae65c77a016e0e3631b0d8e499b85', -1, 1529905580, 1529905580, '36e11fbc', -9, 0, 0)

Line : 187
File : sessions.php