When accessing Linux File Manager, the following error is displayed:
Invalid backend configuration. Readable volumes not available.
During the upgrade, the configuration files of ProFTPd were overwritten. The new ProFTPd configuration file does not contain a directive specifying the range of passive ports in the TLS section.
Modify the configuration file in the directory
/usr/local/etc/proftpd_vhost_confs_pem/ on the web server and add the line
PassivePorts 49152 65534
... <IfModule mod_tls.c> TLSEngine on PassivePorts 49152 65534 ...
Save the file and restart the service:
# service proftpd restart