phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('c3a51e1b01be5cd14c0db2b5799c2648', -1, 1539861696, 1539861696, '3650bc57', -8, 0, 0)

Line : 187
File : sessions.php