xen-hvmcrash: 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/xen-hvmcrash - from package: xen-utils-4.4

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

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