cf-upgrade: 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/lib/debug/usr/sbin/cf-upgrade - from package: cfengine3-dbg
/usr/sbin/cf-upgrade - from package: cfengine3

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

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