nghttpx: 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/sbin/nghttpx - from package: nghttp2

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

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