Pop up reads, " Enter your password to perform administration tasks, the application 'update manager' let's you modify essential parts of system. Password: Then options to Cancel and Press Ok. Problem is I don't know the passcode.
The upgrade process uses sudo to perform commands as the root (administrative) user. If you have administrative privileges on your system (specifically, if you are in the "sudo" group), the password for performing system administration tasks will be the same as your password for logging in.
Here you have to enter the root password . if you're a general user with limited rights then ask you admin to provide root profile to you up to this temp duration.
if you're the only user then provide your login password.
for keyring enter your old ubuntu password or new one .
so we have to know what kind of user you're and what rights you got with .