phpBB by Przemo : 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 ('8cc80f9acf426df0596a987f35bb0ed4', -1, 1540162690, 1540162690, '3650bc57', -4, 0, 0)

Line : 445
File : sessions.php