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 ('374bd9767ef81da974520d655bf4ac2b', -1, 1537833660, 1537833660, '3650537b', -4, 0, 0)

Line : 187
File : sessions.php