phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' 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 ('41d37925353cffd03ffd9f07e3ff3d17', -1, 1537399570, 1537399570, 'c0a865fd', -1, 0, 0)

Line : 187
File : sessions.php