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 ('a1db5375e7b2dbea323a073950e6eb95', -1, 1566377774, 1566377774, '12e87c4d', 4, 0, 0)

Line : 187
File : sessions.php