Network requests not blocked for short period after browser start.

[kasper93]

Describe the issue

Looks like browser can bypass uBlock for the short period of time, probably before extension is fully initialized. I noticed this when restarting browser for update, on session restore page will have ads not blocked.

One or more specific URLs where the issue occurs

I tested with hltv.org but any site will do.

Steps for anyone to reproduce the issue

1. Go to any page where network request is blocked by uBlock.
2. Restart browser - SHIFT+F2 and type restart --nocache
3. Browser will restart and restore previous tabs. But loaded tab will not have ads blocked, because network request were made probably before uBlock is ready.

Your settings

• OS/version: Windows 10
• Browser/version: Firefox Nightly (20170904100131)
• uBlock Origin version: 1.14.8

[Atavic]

It's a browser issue, open it in offline mode to prevent possible leaks.

[Atavic]

Also see: #1913

[uBlock-user]

Open Advanced settings page, set suspendTabsUntilReady to true and restart browser.

[gorhill]

Duplicate of #1327.

[gwarser]

Open Advanced settings page, set suspendTabsUntilReady to true and restart browser.

Sadly, not work for me any more.

• Cookies must be allowed on UBO settings page, for this settings to be remembered between sessions. Offline Website Data must not be cleared on browser close.
• Even with cookies allowed I end up with first tab and address bar being blank. URL only flashes for a moment and then disappear leaving first visible tab unusable.

[gorhill]

https://bugzilla.mozilla.org/show_bug.cgi?id=1378459

[gorhill]

Something else I could experiment with: Firefox's webRequest API allows to return Promise to tell whether a request should be blocked or not. uBO could make use of this and resolve all the pending Promises once all the filters are loaded. I have no clue if that would work though, just that conceptually that seems correct.

[luxoflux]

@gorhill
Did you ever get around to trying that experiment?

[luxoflux]

I found that setting the browser to clear cache on exit fixes this issue for me. Good enough.

Tested with 57b9 and 58.0a1 (2017-10-19).