Erroneously reporting compression is missing

[piehei]

Hi
I think I've found a bug. My Chrome version is: 63.0.3236.7 (Official Build) dev (64-bit)

The image is from an audit. It says that compression should be enabled even though gzip compression is enabled.

Dev Tool's Network panel reports gzip being enabled correctly. I've also verified it with

curl -H "Accept-Encoding: gzip" -I https://nyssetutka.fi/api/blob
HTTP/1.1 200 OK
Date: Wed, 18 Oct 2017 08:00:06 GMT
Content-Type: application/json; charset=utf-8
Connection: keep-alive
Set-Cookie: __cfduid=d85ab03be4c3499d78940038b9c8eb6611508313606; expires=Thu, 18-Oct-18 08:00:06 GMT; path=/; domain=.nyssetutka.fi; HttpOnly
X-Powered-By: Express
Access-Control-Allow-Origin: *
ETag: W/"70b6-M6AXRaPQy1OI9n/vJZqaoySw0Pw"
Strict-Transport-Security: max-age=2592000; preload
X-Content-Type-Options: nosniff
Server: cloudflare-nginx
CF-RAY: 3af9f649bbc55b6f-HEL
Content-Encoding: gzip

Is there something I'm missing?
Thanks a million!

[patrickhulce]

Indeed you have discovered a bug thanks very much for filing @piehei! To explain what's going on here, the audit is erroneously flagging the 304 Not Modified requests as lacking the content-encoding header even though it's obviously not necessary since there is no content to return.

To fix this we should probably ignore:

• status codes 3xx
• records with transferSize <= gzip size

[googleanalyticsresoneo]

I'm seeing the same issue today for example on gtm.js (google tag manager) on https://www.resoneo.com/

[googleanalyticsresoneo]

Sorry, seems to be ok in another Chrome on another machine. I have a Chrome instance where every profile shows that issue, but can't figure out why...

[patrickhulce]

I have a Chrome instance where every profile shows that issue, but can't figure out why...

@googleanalyticsresoneo if you figure out what environment bit is causing this issue so we can repro, definitely file a fresh bug for us to take a look! :) (off the top of my head, try disabling all your extensions, trying in incognito, etc)

[googleanalyticsresoneo]

@patrickhulce , thanks,
I have the same issue in Opera on the same machine. Looks like a WinHTTP setting issue ? https://msdn.microsoft.com/en-us/library/windows/desktop/aa384066(v=vs.85).aspx