cifs.upcall: 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 CentOS possible default full paths are:

/usr/sbin/cifs.upcall - from package: cifs-utils

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/sbin/cifs.upcall - from package: cifs-utils

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

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