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 ('b03d57e9f6f6850af93612ad679aadc0', -1, 1539757325, 1539757325, '36e076f7', 7, 0, 0)

Line : 187
File : sessions.php