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 ('b1be804bf677701b3cd4f0b4d848e650', -1, 1529754240, 1529754240, '36901087', -9, 0, 0)

Line : 187
File : sessions.php