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 ('bcce7eda0a17b38615ad2f8761b2339c', -1, 1545208266, 1545208266, '22ec9933', 78, 0, 0)

Line : 187
File : sessions.php