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 ('637bd80d933d308b78aad8ef797437ac', -1, 1544927029, 1544927029, '36a4c6f0', -7, 0, 0)

Line : 187
File : sessions.php