Comment 4 for bug 1385599

Contrary to ncftp, lftp wants to use ssl if it is offered by the server which makes some sense.
duplicity option "--ssl-no-check-certificate" does not make any change.

WORKAROUNDS:
-switch off ssl support in your FTP server if you can if you don't need it for anything else
-add your self-signed certificate to lftp via its config file:
http://www.versatilewebsolutions.com/blog/2014/04/lftp-ftps-and-certificate-verification.html (not tested)
-disable lftp certificate verification ("set ssl:verify-certificate no" in the config file)

Unfortunately I wasn't able to disable SSL in LFTP. "ftp:ssl-allow false" in lftp config file does not make any change.

Not a really bad bug but still unexpected behaviour with the change to lftp for people using plain ftp whose servers are offering ssl and have a self-signed certificate.