Ubuntu – Why won’t the FTP server let me upload

Probably you has to set the folder's permission for that folder properly For example: If you want to upload a file to folder "testing" using user "MyUser" you have to set write and read permission to MyUser in Testing Folder.

Please avoid storing and transmitting credentials/passwords in plain text.

Instead setup SSH with public key only authorization and use scp or rsync for file transfer. Also let the postgres user himself do the backup via a cronjob (which is the answer to your last question from there), see Ubuntuusers.de Wiki on cron.

Example for a postgres crontab:

# Shell variable for cron
SHELL=/bin/bash

# PATH variable for cron
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# Backup some database from sunday to friday, compress with xz, hash with md5, delete obsolete backups after 40 days
0 3 * * SUN-FRI dump="some-database-$(date +\%Y\%m\%d-\%H\%M)-daily.sql"; cd /var/backups/postgres; pg_dump -Fc -Z0 some-database | xz -6 > ${dump}.xz; md5deep -kl ${dump}.xz > ${dump}.xz.md5; find -name "some-database*daily.sql.xz*" -mtime +40 -delete

Backing up files with tar as your Openbravo ERP or www-data user should be as easy as the above.

Edit: I recommend trying zstd instead of xz as a compressor, it has about 20 levels and is almost as good as the highest xz level on its highest level and still significantly faster.