1660108 - NS_ERROR_FAILURE: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIUrlClassifierBlockedChannel.topLevelUrl] trackingProtection.js:41

Status: RESOLVED FIXED

(Web Compatibility :: Interventions, defect, P3)

Description

[Rob Wu [:robwu]]

bug 1658673 shows that it is possible to get the following error

NS_ERROR_FAILURE: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIUrlClassifierBlockedChannel.topLevelUrl] trackingProtection.js:41
observe jar:file:///opt/firefox-nightly/browser/features/[e-mail]!/experiment-apis/trackingProtection.js:41

at https://searchfox.org/mozilla-central/rev/6cc48251bb97600fdf11a5b4c5f621bfc8606d55/browser/extensions/webcompat/experiment-apis/trackingProtection.js#41

NS_ERROR_FAILURE is indeed a potential error from https://searchfox.org/mozilla-central/rev/23dd7c485a6525bb3a974abeaafaf34bfb43d76b/netwerk/url-classifier/ChannelClassifierService.cpp#97,105,113,118

From the code, it seems that a potential way to trigger the issue is to send a request from context that isn't a browsing context. Bug 1658673 is an example, here is another minimal example:

STR

1. Set Tracking Protection to strict at about:preferences -> Privacy.
2. Run the following code snippet from e.g. example.com:

new Worker(`data:,fetch("https://pbs.twimg.com/", {mode: "no-cors"})`);

3. Look at the global JS console

Expected:

• No error (besides TypeError: NetworkError when attempting to fetch resource. to indicate that the request was blocked by Tracking Protection)

Actual:

• The error from above, ... (NS_ERROR_FAILURE) [nsIUrlClassifierBlockedChannel.topLevelUrl] trackingProtection.js:41 ...

Comment 1

[Mike Taylor [:miketaylr]]

Tom, can you take a look please?

Comment 2

[Thomas Wisniewski [:twisniewski][PTO until Mar.16]]

Fixed with the in the parent bug (https://bugzilla.mozilla.org/attachment.cgi?id=9175540).