phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO r2ok_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('6350c8d6e8da5bfb84f576087e689616', -1, 1524226875, 1524226875, '36506778', -9, 0, 0)

Line : 187
File : sessions.php