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 ('3a1f2966f25b4ca50fd4ab12a9eb26d1', -1, 1537968849, 1537968849, '369ec7d9', -8, 0, 0)

Line : 187
File : sessions.php