partclone.btrfs: 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/sbin/partclone.btrfs - from package: partclone

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