ExtensionCore.py: 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/cinnamon/cinnamon-settings/bin/ExtensionCore.py - from package: cinnamon-common

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

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