ardour2-session_exchange.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/bin/ardour2-session_exchange.py - from package: ardour

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

Error in other languages:
ardour2-session_exchange.py: bevel nie gevind nie
ardour2-session_exchange.py: comandă negăsită
ardour2-session_exchange.py: comando não encontrado
ardour2-session_exchange.py: commande introuvable
ardour2-session_exchange.py: command not found
ardour2-session_exchange.py: käsku ei ole
ardour2-session_exchange.py: không tìm thấy lệnh
ardour2-session_exchange.py: komanda nerasta
ardour2-session_exchange.py: Kommando nicht gefunden.
ardour2-session_exchange.py: kommandot finns inte
ardour2-session_exchange.py: komut yok
ardour2-session_exchange.py: nie znaleziono polecenia
ardour2-session_exchange.py: níor aimsíodh an t-ordú
ardour2-session_exchange.py: no se encontró la orden
ardour2-session_exchange.py: no s'ha trobat l'ordre
ardour2-session_exchange.py: opdracht niet gevonden
ardour2-session_exchange.py: parancs nem található
ardour2-session_exchange.py: perintah tidak ditemukan
ardour2-session_exchange.py: príkaz nenájdený
ardour2-session_exchange.py: příkaz nenalezen
ardour2-session_exchange.py: команда не найдена
ardour2-session_exchange.py: командата не е открита
ardour2-session_exchange.py: 命令找不到
ardour2-session_exchange.py: コマンドが見つかりません