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 ('969085983797d1d877a6253ec3c4cf4f', -1, 1540245626, 1540245626, '369c27f5', -1, 0, 0)

Line : 187
File : sessions.php