I have not updated my Android Studio for a while and am presented with this dialog box when trying to update:
I was on version 0.4.4 trying to update to 0.5.8. At first I thought I would have to do it manually, but I found a workaround.
First I had to update to the latest version in the dev channel, which I switched to in the IDE setting under file -> settings -> updates. This allowed me to automatically update to 0.5.2. Android Studio then detected the 0.5.8 build and allowed me to update automatically.
YMMV, and so will your versions when you see this, but maybe try not going from a really old version straight to the recent canary channel build.