1530887 - .png images show up in Firefox as .webp images

Status: RESOLVED FIXED

(Core :: Networking: HTTP, defect)

Description

[Moltres Rider]

User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0

Steps to reproduce:

View several images that are in PNG format on various websites

Actual results:

Firefox displays them as .webp images despite the fact that these images found on the web are png files

Expected results:

If the original format of these images are .png, Firefox should display them and download them as .png not .webp.

Comment 1

[Gingerbread Man]

(In reply to Moltres Rider from comment #0)

View several images that are in PNG format on various websites

Please provide an example.

You're almost certainly looking at a page that uses PNG as a fallback; since WEBP is now supported, that's what you're seeing instead.

Comment 2

[Moltres Rider]

https://vignette.wikia.nocookie.net/pokemongo/images/0/00/Ho-Oh.png

https://cdn3-www.gamerevolution.com/assets/uploads/2018/12/pokemon-go-lugia-and-ho-oh.png

Both these display and download as .webp despite being PNG files.

Comment 3

[Gingerbread Man]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0
20190211233335

:baku since you're involved with bug 1526731, you may be able to clear this up.

(In reply to Moltres Rider from comment #2)

https://vignette.wikia.nocookie.net/pokemongo/images/0/00/Ho-Oh.png

Firefox instructs the server that WebP is preferred, and the server sends a WebP file. The only thing I find off is that the address bar retains the ….png URL. I suspect this might bizarrely be expected behavior for a 200 OK response with the filename specified in the Content-Disposition header.

Request headers:

Host: vignette.wikia.nocookie.net
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Upgrade-Insecure-Requests: 1

Partial response headers:

HTTP/2.0 200 OK
content-type: image/webp
content-length: 19272
content-disposition: inline; filename="Ho-Oh.webp"; filename*=UTF-8''Ho-Oh.webp
…

https://cdn3-www.gamerevolution.com/assets/uploads/2018/12/pokemon-go-lugia-and-ho-oh.png

Appears to be the same situation:

Request headers:

Host: cdn3-www.gamerevolution.com
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Upgrade-Insecure-Requests: 1
TE: Trailers

Partial response headers:

HTTP/2.0 200 OK
content-type: image/webp
content-length: 295266
content-disposition: inline; filename="pokemon-go-lugia-and-ho-oh.webp"
…

Comment 4

[Alice0775 White]

I can reproduce the issue on 65.0.1 windows10.
However, I cannot reproduce it anymore on 66.0b11 and Nightly670a1 windows10.

Comment 5

[Alice0775 White]

(In reply to Alice0775 White from comment #4)

I can reproduce the issue on 65.0.1 windows10.
However, I cannot reproduce it anymore on 66.0b11 and Nightly670a1 windows10.

Fixed range:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=1760e005cecc1f7eedd1e6e4c022d73375d12327&tochange=2a7dce7a42ea0527694c978e98d9af1687aecb36

This seems to have already been fixed by bug 1417463

Comment 6

[Gingerbread Man]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:67.0) Gecko/20100101 Firefox/67.0
20190227163104

(In reply to Alice0775 White from comment #5)

Fixed range:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=1760e005cecc1f7eedd1e6e4c022d73375d12327&tochange=2a7dce7a42ea0527694c978e98d9af1687aecb36

Thank you for making the effort.