mptopdf: 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 CentOS possible default full paths are:

/usr/bin/mptopdf - from package: texlive-context

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/mptopdf - from package: texlive-latex-base

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

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