deb-systemd-invoke: 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/deb-systemd-invoke - from package: init-system-helpers

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

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