STR:

• Go to https://stackblitz.com/edit/rxjs-yo2jz5?file=index.html

ER:

• A green square.

AR:

• Right tab doesn't load, there's a cross-origin error there.

This breakage can be fixed by changing cookiebehavior to 4, so this is only related to dFPI.

It looks like the right tab is put under a third-party iframe https://rxjs-yo2jz5.stackblitz.io and its storage is partitioned. And it needs storage access to show the content properly.

I think the proper solution is to ask the website to use the StorageAccessAPI.

Steve, do you know if we have contacted them about this issue? Thanks.

As far as I know we have not. We'll have to see if stpeter or webcompat folks have a contact.

Filed an issue on their GitHub repo: https://github.com/stackblitz/core/issues/1374

https://hg.mozilla.org/mozilla-central/rev/f1b824815906

Verified as fixed on the latest Nightly 95.0a1 and on Firefox 94 beta 1 (having the pref network.cookie.cookieBehavior set to 5) - the green square is properly displayed on stackblitz.com.
Tested on Windows 10 x64, Ubuntu 20.04 x64, and macOS Big Sur 11.6.

StackBlitz staffer here. Sorry if this is not the right venue, but is there a way for us to test in Firefox without this shim?

We have features that are breaking because of it (e.g. https://github.com/stackblitz/core/issues/1679 and a bunch of duplicate reports), because they rely on Service Workers, and we can't test fixes in Firefox because the shim seems to apply no matter what.

I tried setting a few about:config settings, but am not seeing a difference. I’m still getting a warning in the Console with

Service Workers are disabled by Firefox on this page to prevent breakage. See https://bugzilla.mozilla.org/show_bug.cgi?id=1668408 for details.

The about:config options I tried (in Firefox Nightly and stable) were:

• extensions.webcompat.enable_shims = false
• extensions.webcompat.perform_injections = false
• extensions.webcompat.perform_ua_overrides = false

(In reply to Florens Verschelde :fvsch from comment #11)

StackBlitz staffer here. Sorry if this is not the right venue, but is there a way for us to test in Firefox without this shim?

We have features that are breaking because of it (e.g. https://github.com/stackblitz/core/issues/1679 and a bunch of duplicate reports), because they rely on Service Workers, and we can't test fixes in Firefox because the shim seems to apply no matter what.

I tried setting a few about:config settings, but am not seeing a difference. I’m still getting a warning in the Console with

Service Workers are disabled by Firefox on this page to prevent breakage. See https://bugzilla.mozilla.org/show_bug.cgi?id=1668408 for details.

The about:config options I tried (in Firefox Nightly and stable) were:

• extensions.webcompat.enable_shims = false
• extensions.webcompat.perform_injections = false
• extensions.webcompat.perform_ua_overrides = false

Navigate to about:compat and click "Disable" for StackBlitz. That should disable the shim for the current browser session.

Thanks a bunch :)

Do we still need this shim, now that we support partitioned service workers? I've tested the original STR on Nightly with the shim disabled via about:compat and it seems to load just fine.

Yes, we have enabled the partitioned service workers since Fx 105. And I can confirm that it fixes this issue on stackblitz with the shim disabled. So, I think we can remove the shim.

Awesome! I'll remove it in the bug 1795692.