mtp-filetree: 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/bin/mtp-filetree - from package: mtp-tools

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

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