phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '0' 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 ('f078e7f05ab4ed856106dcb9df9d76b1', -1, 1545222787, 1545222787, '36ecea3c', 77, 0, 0)

Line : 187
File : sessions.php