TLS session of data connection has not resumed or the session does not match the control connection
You may receive this error when backing-up files to FileZilla server using SyncBackPro/SE. This is due to the new ‘TLS session resumption’ security feature enabled by default in FileZilla server 0.9.51 (or newer) version.
To resolve the error, you can either deactivate ‘Require TLS session resumption on data connection’ (from: FileZilla sever options > General Settings > ‘FTP over TLS settings’ page) or change the FTP engine in the profile to WeOnlyDo (under: Modify profile > FTP page).