Module 4 error using vstfpd

File transfers successfully for vsftpd_v4, vsftpd_v5, vsftpd_v6, vsftpd_v7. But for vsftpd_v2 and vsftpd_v3 I get following error when using ftp:-
421 Service not available, remote server has closed connection

This is the third time I am posting this doubt. Every time I post it, it automatically gets removed.

same problem with me while transfer file!!
Please anyone help us!!!

Hey it’s simple this thing would be error if it will be happening with every version of binary executable but if it is happening only with these 2 versions there has to be some reasons and may be these error are mentioned their intentionally to figure out something or to make you learn something in next milestones so be patient and also read tasks and instructions of other milestones you will figure out.