svn-upgrade: 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/svn-upgrade - from package: svn-buildpackage

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

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