grub-render-label: 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/grub-render-label - from package: grub-common

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

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