By Default, root is not able to access ftp because it's name in the list of /etc/ftpusers or /etc/vsftpd/ftpusers
Remove root from the list. Save the file.
Restart vsftpd.
root will be able to log-in using ftp.
If you are using CentOS, fedora or RHEL and still you are not able to log in as root in your ftp server.
Add following line in the file vsftpd.conf
userlist_deny=YES
Remove user root in file /etc/vsftpd/user_list
Restart vsftpd.
root should be able to log-in using ftp.
Remove root from the list. Save the file.
Restart vsftpd.
root will be able to log-in using ftp.
If you are using CentOS, fedora or RHEL and still you are not able to log in as root in your ftp server.
Add following line in the file vsftpd.conf
userlist_deny=YES
Remove user root in file /etc/vsftpd/user_list
Restart vsftpd.
root should be able to log-in using ftp.
You can see the solution in the following video.