I'm sure you're aware, but as a workaround, you can change the window size, e.g.

Capybara.register_driver :apparition do |app|
  Capybara::Apparition::Driver.new(app,
    …
    window_size: [1024, 12345],
  )
end

To be clear, I'm not saying this isn't a bug :)

I got the same error. I think the following line is the problem:

Here is the context:

        elsif options[:full]
          evaluate <<~JS
            { width: document.documentElement.clientWidth, height: document.documentElement.clientHeight}
          JS
        else

document.documentElement.clientHeight is not the full high of the content. It is the height of the window part. If I use the selector: 'html' option I got the full screenshot.