fai-debconf: 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/fai-debconf - from package: fai-client

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

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