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 ('9cf14377d35b1d05cd0d624846a9db1f', -1, 1534470430, 1534470430, '36e137ae', -4, 0, 0)

Line : 187
File : sessions.php