kwin_gles: 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/kwin_gles - from package: kde-window-manager

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

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