I recently spent a bunch of time debugging an issue where my environment had AWS_SECRET_ACCESS_KEY set for reasons unrelated to the electron project I was working on. This resulted in a very unhelpful error: Error: Please specify "bucket" for "s3" update server which seemed crazy to me because nothing anywhere in my project used s3 or aws. I eventually discovered #1270 which led me to check my env, where I found the AWS_SECRET_ACCESS_KEY.

I suggest that you add an option to disable all implicit detection of build or publish settings, I would much rather specify everything explicitly, as I find this type of magic auto-detection fails in very hard to debug ways. Otherwise, I suggest adding info about what settings have been auto-detected and how, for example: Attempting to publish to s3 because AWS_SECRET_ACCESS_KEY is set. Error: Could not find "bucket" setting.