PB "lftp Erreur fatale: Certificate verification: Not trusted"

SOLUTION 1) no certificate check

echo "set ssl:verify-certificate no" >> ~/.lftp/rc

will solve the problem if you dont want the certificate to be checked

SOLUTION 2) The secure solution with certificate is

What worked for me step by step with lftp:

get certificate of host with openssl s_client -connect <ftp_hostname>:21 -starttls ftp, at the begining of result I got something like -----BEGIN CERTIFICATE-----
MIIEQzCCAyu.....XjMO
-----END CERTIFICATE-----
copy that -----BEGIN CERTIFICATE-----
MIIEQzCCAyu.....XjMO
-----END CERTIFICATE----- into /etc/ssl/certs/ca-certificates.crt
Into lftp configuration reference this certificate file adding to /etc/lftp.conf for systemwide set ssl:ca-file "/etc/ssl/certs/ca-certificates.crt"
and then do your sync or whatever with lftp, on my case it is lftp -u "${FTP_USER},${FTP_PWD}" ${FTP_HOST} -e "set net:timeout 10;mirror ${EXCLUDES} -R ${LOCAL_SOURCE_PATH} ${REMOTE_DEST_PATH} ; quit"