When I run the command "sudo spi -U", it runs fine and does the update as expected. Below is the screenshot of the output. So, when I click the system tray icon for update notifier, for some reason, the sudo or gksu prompt is not launching.
But, this is not happening which is why I entered the post. When I click the update notifier from System tray, I get the dialog box for "Proceed with updating?". When I click Yes, nothing happens. However, if I run the command "sudo spi -U", it is able to find the updates and installs fine. Something is not working correctly with the update notifier. I am not sure of a way to debug this.
I just had such a problem in Slackel. Update-Notifier could not find
zenity even so it was present. I upgraded zenity and Update-Notifer
worked again.
The way I found this out, on a terminal I typed salix-upgrade-notifier
and it said it cannot find zenity.