On OSX 10.13.2, I just tried to use the web UI to upgrade Duplicati from Canary v188.8.131.52 to Canary v184.108.40.206. The web UI showed me there was an upgrade available for the Canary channel, the upgrade downloaded, then…nothing. I don’t even know where the upgrade file went on my filesystem. IIRC, there should have been an “activate” button in the web UI after downloading, but I never saw it.
I tried this several times. In the end,I just downloaded the new .pkg file from github and installed that, but I wanted to report the problem here.