Deprecation: source src

The plan was to add picturefill.js

That is strange behaviour, indeed.

Browsers should prefer the source with the type=”image/webp” over a source without it, when they support webp. So if your Edge browser selects the jpeg, it should mean it does not support webp. When WebP Express is in “Varied image responses” mode, it returns webp images for jpeg requests. But only when the browser has send an Accept header containing “image/webp”, indicating that the browser accepts webp. Your results is thus contradicting.

Which version of Edge are you using? According to caniuse, Edge supports webp in version 18, but not in previous versions.

How does your picture markup look?

I’m assuming that you put WebP Express in Varied image responses mode? (otherwise a jpeg should not return as a webp).

Oh, wait a minute. Could it be that you are using a CDN? Unless set up properly (which not all can), CDN’s doesn’t handle varied image responses. In that case you should use “CDN friendly mode”

• This reply was modified 7 years, 3 months ago by rosell.dk.