qaptworker: 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/qaptworker - from package: libqapt-runtime

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

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