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 ('781bc1c3d0037c6918601f7523adf0b7', -1, 1539928589, 1539928589, '36e11a2c', 45, 0, 0)

Line : 187
File : sessions.php