mbconv: 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

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/mbconv - from package: libmoe1.5

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