phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('5d059f731a81f89f0d1fd3acfc815af1', -1, 1548017453, 1548017453, '36e2401e', -8, 0, 0)

Line : 172
File : sessions.php