ext4fixup: 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/ext4fixup - from package: android-tools-fsutils

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

Error in other languages:
ext4fixup: bevel nie gevind nie
ext4fixup: comandă negăsită
ext4fixup: comando não encontrado
ext4fixup: commande introuvable
ext4fixup: command not found
ext4fixup: käsku ei ole
ext4fixup: không tìm thấy lệnh
ext4fixup: komanda nerasta
ext4fixup: Kommando nicht gefunden.
ext4fixup: kommandot finns inte
ext4fixup: komut yok
ext4fixup: nie znaleziono polecenia
ext4fixup: níor aimsíodh an t-ordú
ext4fixup: no se encontró la orden
ext4fixup: no s'ha trobat l'ordre
ext4fixup: opdracht niet gevonden
ext4fixup: parancs nem található
ext4fixup: perintah tidak ditemukan
ext4fixup: príkaz nenájdený
ext4fixup: příkaz nenalezen
ext4fixup: команда не найдена
ext4fixup: командата не е открита
ext4fixup: 命令找不到
ext4fixup: コマンドが見つかりません