switch_root: 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:

/sbin/switch_root - from package: util-linux-ng

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

On Debian possible default full paths are:

/sbin/switch_root - from package: util-linux

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

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