newuidmap: 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/newuidmap - from package: uidmap

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

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