debconf-apt-progress: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/debconf-apt-progress - from package: debconf

You may install the required package with command apt-get install {package}

Error in other languages:
debconf-apt-progress: bevel nie gevind nie
debconf-apt-progress: comandă negăsită
debconf-apt-progress: comando não encontrado
debconf-apt-progress: commande introuvable
debconf-apt-progress: command not found
debconf-apt-progress: käsku ei ole
debconf-apt-progress: không tìm thấy lệnh
debconf-apt-progress: komanda nerasta
debconf-apt-progress: Kommando nicht gefunden.
debconf-apt-progress: kommandot finns inte
debconf-apt-progress: komut yok
debconf-apt-progress: nie znaleziono polecenia
debconf-apt-progress: níor aimsíodh an t-ordú
debconf-apt-progress: no se encontró la orden
debconf-apt-progress: no s'ha trobat l'ordre
debconf-apt-progress: opdracht niet gevonden
debconf-apt-progress: parancs nem található
debconf-apt-progress: perintah tidak ditemukan
debconf-apt-progress: príkaz nenájdený
debconf-apt-progress: příkaz nenalezen
debconf-apt-progress: команда не найдена
debconf-apt-progress: командата не е открита
debconf-apt-progress: 命令找不到
debconf-apt-progress: コマンドが見つかりません