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 ('7523901d0114b9c338a0f42ec8e8ba02', -1, 1540307334, 1540307334, '365ca369', 22, 0, 0)

Line : 187
File : sessions.php