libxl-save-helper: 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/xen-4.4/bin/libxl-save-helper - from package: xen-utils-4.4

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

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