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 ('987fc8c9f7e5ab717c5c5031c1f57048', -1, 1529905845, 1529905845, '36e11fbc', 54, 0, 0)

Line : 187
File : sessions.php