1982934 - When navigating from an internal page, events of webRequest.filterResponseData() do not fire for main_frame responses.

Status: NEW

(WebExtensions :: Request Handling, defect, P3)

Description

[nines [:nines]]

Attachment: example-extension.zip

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:142.0) Gecko/20100101 Firefox/142.0

Steps to reproduce:

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:143.0) Gecko/20100101 Firefox/143.0
Build ID: 20250813091044

1. Load the attached extension via "about:debugging#/runtime/this-firefox".
2. Click “Inspect” and open the console.
3. Visit "https://www.google.com/" and verify that an ArrayBuffer is logged.
4. Visit "about:preferences".
5. Visit "https://www.google.com/" again.

Actual results:

Only the URL is logged.

Expected results:

The URL, an ArrayBuffer, and the string "closed" are logged.

Comment 1

[Rob Wu [:robwu]]

The events do not fire because internally the request is considered redirected for some reason.

If you modify the test case and add filter.onerror = e => console.error(filter.error);

... then the displayed error is (confusingly) "Invalid request ID"
This error is confusing due to bug 1683862.

I tried out the STR with about:addons, about:config, about:preferences, about:logo can can confirm the observations.
On the other hand, on about:newtab, about:privatebrowsing, https://addons.mozilla.org/ the issue does not happen.

Based on this, I think that the actual issue is happening when a navigation is triggered from a tab in a non-remote process to a remote process.
To test this hypothesis, I set extensions.webextensions.remote to false in about:config, restarted Firefox, opened the manifest.json link of the extension, and indeed, the issue also reproduced there.

Next step here is to investigate what is happening and triage further.

Comment 2

[Rob Wu [:robwu]]

This bug also reminds me of bug 1806476, but that was about navigating from about:newtab or about:home to someplace else, and in the above comment I confirmed that this specific issue does not happen with about:newtab.

I'll investigate this a bit more.

Comment 3

[ThomazPom]

I encountered this issue in UltimaDark WebExt and documented a workaround here:
https://github.com/ThomazPom/Moz-Ext-UltimaDark/issues/171#issuecomment-3563934115

Other Bugzilla reports where I’m confident it’s the same issue:
https://bugzilla.mozilla.org/show_bug.cgi?id=1561604
https://bugzilla.mozilla.org/show_bug.cgi?id=1806476

To isolate the problem, I tested every relevant about: page to determine which ones trigger the filter failure.
Here is the detailed overview:

initialUrl	hasIssue	hasIssueBool
about:blank	No filter issue	false
about:welcome	No filter issue	false
about:studies	No filter issue	false
about:protections	No filter issue	false
about:privatebrowsing	No filter issue	false
about:newtab	No filter issue	false
about:loginsimportreport	No filter issue	false
about:logins	No filter issue	false
about:home	No filter issue	false
about:compat	No filter issue	false
about:certificate	No filter issue	false
about:about	Has filter issue	true
about:windows-messages	Has filter issue	true
about:webrtc	Has filter issue	true
about:url-classifier	Has filter issue	true
about:unloads	Has filter issue	true
about:third-party	Has filter issue	true
about:telemetry	Has filter issue	true
about:sync-log	Has filter issue	true
about:support	Has filter issue	true
about:serviceworkers	Has filter issue	true
about:robots	Has filter issue	true
about:profiling	Has filter issue	true
about:profiles	Has filter issue	true
about:processes	Has filter issue	true
about:preferences	Has filter issue	true
about:policies	Has filter issue	true
about:networking	Has filter issue	true
about:mozilla	Has filter issue	true
about:memory	Has filter issue	true
about:logo	Has filter issue	true
about:logging	Has filter issue	true
about:license	Has filter issue	true
about:downloads	Has filter issue	true
about:debugging#/setup	Has filter issue	true
about:crashes	Has filter issue	true
about:config	Has filter issue	true
about:checkerboard	Has filter issue	true
about:cache	Has filter issue	true
about:buildconfig	Has filter issue	true
about:addons	Has filter issue	true