1935691 - Firefox is NOT set as the default browser even if the “set_default_browser” attribution campaign id is contained by the installer

Status: VERIFIED FIXED

(Firefox :: Messaging System, defect, P1)

Description

[Valentin Bandac [:vbandac], Ecosystem QA]

[Affected versions]:

• Firefox Developer Edition 134.0b5 (BUILD ID #20241204091850)

[Affected Platforms]:

• Windows 10 x64
• Windows 11 x64

[Prerequisites]:

• Download the Firefox installer containing the “set_default_browser” attribution campaign id using this link.

[Steps to reproduce]:

1. Install the browser using the installer from the prerequisites.
2. Navigate to the “about:welcome” page and observe the available options on the first screen.
3. Navigate to the “about:preferences” page and check if Firefox is set as default.

[Expected result]:

Step 2: The “Set Firefox as default browser” option is not displayed on the first screen of the Onboarding Tour.
Step 3: The Firefox browser is set as default.

[Actual result]:

Step 2: The “Set Firefox as default browser” option IS displayed on the first screen of the Onboarding Tour.
Step 3: The Firefox browser is NOT set as default.

[Notes]:

• I have verified and can confirm that the “set_default_browser” attribution campaign id is present on the “about: telemetry#search=attribution” page.
• I have also verified that Firefox is NOT set as the default browser on the OS settings page.
• This issue is not reproducible on any Firefox Beta 134.0b1 or later builds if the attribution code is set by modifying the “postSigningData” file to contain the “campaign%3Dset_default_browser” string.

Comment 1

[Meg Viar]

Thanks for flagging this issue. The feature was working as expected when I tested on Windows 11 Pro (version 23H2, build 22631.4460, VM) and Windows 10 Pro (version 22H2, build 19045.5131, physical machine), Windows 11 Pro version 10.0.22631, build 22631), .

On Windows 11 (version 10.0.26100, build 26100), the action triggered launching the system prompt to set default, but it appears one-click set to default did not work on this build. This resulted in the same outcome you saw in your testing above (setting default was included in the action list on about:welcome and the browser was not set as default until you completed the steps from the system prompt.

Could you provide the version and build number for the Windows machines where you encountered the issue? Also, could you share whether the preference trailhead.firstrun.didHandleCampaignAction is set after you visit about:welcome in the steps described above to help confirm that this is, indeed, an issue related to the one-click set to default functionality?

Comment 2

[Meg Viar]

Please see questions in comment above. Thanks again for your help with this.

Comment 3

[Valentin Bandac [:vbandac], Ecosystem QA]

We encountered this issue on Windows 10 Pro (version 22H2, build 19045.5198) and Windows 11 Enterprise (version 23H2, build 22631.4460), on Firefox Developer Edition 134.0b5 (BUILD ID #20241204091850).
However, it seems that the issue is no longer reproducible on Firefox Developer Edition 134.0b7 (BUILD ID #20241206102218) using the same stub installer that you provided and the same steps as before.
I can confirm the following after visiting the “about:welcome” page:

• The “Set Firefox as default browser” option is not displayed in the action list on about:welcome
• Firefox is set as default browser
• The “trailhead.firstrun.didHandleCampaignAction” pref is set with the “true” value

Considering the above, I think we can close this issue.

Comment 4

[Valentin Bandac [:vbandac], Ecosystem QA]

Based on my last comment I am closing this issue as Resolved - Fixed.