atril-thumbnailer: 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/atril-thumbnailer - from package: atril

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

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