ssh-askpass-noinput: 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

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/ssh-askpass-noinput - from package: ssh-agent-filter

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