convertsegfilestopdf: command not found

Have You tried accessing the binary with the full path?

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/convertsegfilestopdf - from package: leptonica-progs

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