Why doesn't vsftpd only accept files from one client?

Question

FTP

Good day to all. The vsftpd server is set up and works great with FileZilla clients and ES explorer on android (same user). But when using my own program, it gives an error "could not create file", although it works fine with other servers (ES Explorer, FileZilla or a server created by standard windows tools). The following entry is in the vsftpd logs:

Mon Nov 21 13:35:58 2016 [pid 10126] [evgenii] OK LOGIN: Client "::ffff:192.168.31.109"
Mon Nov 21 13:35:58 2016 [pid 10132] [evgenii] FAIL UPLOAD: Client " ::ffff:192.168.31.109", "/home/data/ServerD", 0.00Kbyte/sec

Server config:

listen=NO
listen_ipv6=YES
anonymous_enable=NO
local_enable=YES
write_enable=YES
#local_umask=022
dirmessage_enable=YES
use_localtime=YES
connect_from_port_20=YES
secure_chroot_dir=/var/run/vsftpd/empty
rsa_cert_file=/etc/ssl/certs/ssl-cert -snakeoil.pem
rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
ssl_enable=NO

What is the problem?
Thanks in advance for your replies