extensions.dll: 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/share/asp.net-demos/bin/extensions.dll - from package: asp.net-examples

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

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