phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO oka_phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('85e55cf6464a7cb2952ca3e3b81cf7b8', -1, 1550515743, 1550515743, '36d23d29', 6, 0)

Line : 184
File : /home/c128/public_html/talk/includes/sessions.php