Sometimes it is not possible to update to a later version of Avast. However, unwanted encouragements to update persist. The system tray icon, for example, might have a yellow triangle on it and on further investigation you see that you need to update to remove this irritant, but you can’t.
Oh that Avast would provide a button that turns off this behaviour and leaves the poor user, who cannot update Avast to a later version, in peace.
It’s already there…GUI>Settings>Update>tick the desired choice. 
Thank you for the response. I have seen the issue arise even when program updates are set to manual and this is why I felt it necessary to ask the question. Once you pass a point of no return, the behaviour seems irreversible.
I am on version 8 and do not yet wish to make the move to version 9. I am hoping that version 9 offers such compelling benefits in effectiveness that a move is a no-brainer. I am greatly disappointed with the GUI of v9. I found v8 GUI intuitively simple to use which sadly is not the case with v9 GUI.
In spite of setting program update option to manual in version 8, the nagging to update is NOT suppressed. This is very presumptuous of Avast. Not only that but version 9 breaks Opera 12.
If I were a paying customer, I would be extremely angry. As it is, this so called ‘improvement’ is anything but and I will be reverting to version 8. No doubt I will again be nagged to install an unwanted update.
The yellow caution triangle on the system tray icon is crying Wolf when its use is trivialised to warn that a program update has not been installed, presumably because the user has implicitly declined to.
Yup! Avast 9 messes up Opera 12. Ironically, it was the misrendering of this forum which first alerted me. Opera 12 works perfectly with Avast 8.0.1497, as does everything else.
Please do not presume that the latest is better. The final insult is the yellow warning triangle in the Avast system tray icon. That is surely to warn of more important things than the user having consciously declined the use of the later version. If it cannot be suppressed, I will perforce put up with it.
Correction: It appears that an incompatibility with Agnitum Outpost Firewall 8.1.2 may be the problem and that Outpost’s Web Control might be not too happy with Avast 9 Web Shield. Web Control is enormously valuable to me so I will have to stick with Avast 8.
C’est la vie.
Yep! you cant use Outposts web control with avast 9 unless you remove avasts browser protection.
+1 Craig is 100% correct 
Although Outpost offers Web Control even after you have confirmed you are using avast. I have never selected it for many years now as I honestly don’t believe it brings that much to the party.
Avast is more than enough in the way of web protection.