mnemo-convert-to-utf8: 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 CentOS possible default full paths are:

/usr/bin/mnemo-convert-to-utf8 - from package: php-horde-mnemo

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/mnemo-convert-to-utf8 - from package: php-horde-mnemo

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

Error in other languages:
mnemo-convert-to-utf8: bevel nie gevind nie
mnemo-convert-to-utf8: comandă negăsită
mnemo-convert-to-utf8: comando não encontrado
mnemo-convert-to-utf8: commande introuvable
mnemo-convert-to-utf8: command not found
mnemo-convert-to-utf8: käsku ei ole
mnemo-convert-to-utf8: không tìm thấy lệnh
mnemo-convert-to-utf8: komanda nerasta
mnemo-convert-to-utf8: Kommando nicht gefunden.
mnemo-convert-to-utf8: kommandot finns inte
mnemo-convert-to-utf8: komut yok
mnemo-convert-to-utf8: nie znaleziono polecenia
mnemo-convert-to-utf8: níor aimsíodh an t-ordú
mnemo-convert-to-utf8: no se encontró la orden
mnemo-convert-to-utf8: no s'ha trobat l'ordre
mnemo-convert-to-utf8: opdracht niet gevonden
mnemo-convert-to-utf8: parancs nem található
mnemo-convert-to-utf8: perintah tidak ditemukan
mnemo-convert-to-utf8: príkaz nenájdený
mnemo-convert-to-utf8: příkaz nenalezen
mnemo-convert-to-utf8: команда не найдена
mnemo-convert-to-utf8: командата не е открита
mnemo-convert-to-utf8: 命令找不到
mnemo-convert-to-utf8: コマンドが見つかりません