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 ('b9ee14bb35a5c674968fba55f629b3c7', -1, 1542128549, 1542128549, '36eb306a', 39, 0, 0)

Line : 187
File : sessions.php