depythontex3: command not found

Have You tried accessing the binary with the full path?

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/depythontex3 - from package: texlive-extra-utils

You may install the required package with command apt-get install {package}
Error in other languages:
depythontex3: bevel nie gevind nie
depythontex3: comandă negăsită
depythontex3: comando não encontrado
depythontex3: commande introuvable
depythontex3: command not found
depythontex3: käsku ei ole
depythontex3: không tìm thấy lệnh
depythontex3: komanda nerasta
depythontex3: Kommando nicht gefunden.
depythontex3: kommandot finns inte
depythontex3: komut yok
depythontex3: nie znaleziono polecenia
depythontex3: níor aimsíodh an t-ordú
depythontex3: no se encontró la orden
depythontex3: no s'ha trobat l'ordre
depythontex3: opdracht niet gevonden
depythontex3: parancs nem található
depythontex3: perintah tidak ditemukan
depythontex3: príkaz nenájdený
depythontex3: příkaz nenalezen
depythontex3: команда не найдена
depythontex3: командата не е открита
depythontex3: 命令找不到
depythontex3: コマンドが見つかりません