Lighthouse on Chrome Canary incorrectly gives the error 'Content is not sized correctly for the viewport'

Question

The lighthouse audit tool gives the following error: Content is not sized correctly for the viewport

even though this never appears on the normal Chrome

same issue in Version 69.0.3497.100 (Official Build) (64-bit)...

Answer 1

Clicking for more information on this bug takes you to https://developers.google.com/web/tools/lighthouse/audits/content-sized-correctly-for-viewport which defines that this error is due to failure of the condition:

window.innerWidth === window.outerWidth

This is a silly bug (reported to Google also) and to prevent it, just make sure that the DevTools are not stacked to the right of the webpage :)

Sharing to help some other web optimizer who might run into this.

Answer 2

I found that in ChromiumOs (CloudReady) if lighthouse is invoked with Ctrl-Shift-I while viewing the page to be evaluated, and "Toggle device toolbar" (Ctrl-Shift-M), then generate lighthouse report, this error goes away.

However, if lighthouse is invoked from the extension icon (which will run in a separate page, the error is there. I have not found any way to eliminate this superfluous error in that situation.