I think this is a multiple-part question. One is how to specify it, and I agree that it’s not an “option” but an environment variable to set. Next is whether it has any effect, and you’ll probably notice that (at least on Windows) you have fewer Duplicati processes because things like Duplicati.GUI.TrayIcon.exe no longer start in pairs. I think this ties in with the first part. The autoupdater doesn’t replace the base version that’s originally installed, but has it start and check for an installed update (different drive location) then run that, however below is how this environment variable stops the start of possibly-updated child, and runs base:
As an aside, I think options get read after that split-or-not, which is why an environment variable is used.
Downgrading / reverting to a lower version talks about how to remove an update to get to a lower version.
[SOLVED] Is it ok that I see 5 processes of Duplicati in Windows Task manager? talks about processes.
Then there’s the question of whether or not notification of new updates should happen, and I’m not certain that disabling that is within the scope of the AUTOUPDATER_Duplicati_SKIP_UPDATE=1 variable’s function. I’ve had to do somewhat absurd measures like set AUTOUPDATER_Duplicati_URLS=http://127.0.0.1 (which makes sure it can’t find an update on my local computer’s non-existent web server) to stop alerts.
One question is what @rx777 is trying to achieve. There wouldn’t be an alert now about an update from 2.0.4.30 because there’s nothing newer now. Running GUI, one always has time to look at release notes, ignore that update, let it age awhile to see how it goes, etc. If the goal is to avoid buggier canary releases, while waiting for Beta, then change your update channel setting to Beta (or maybe Experimental) instead.
I’d note that there may be a serious bug in 2.0.4.30 and earlier, so updates are not always worth avoiding.