mbsync-get-cert: 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/mbsync-get-cert - from package: isync

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

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