2051921 - Provide a policy that prevents the user from changing the default browser

Status: RESOLVED FIXED

(Firefox :: Enterprise Policies, enhancement, P3)

Description

[edward]

Attachment: Screenshot 2026-07-01 at 13.57.24.png

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:152.0) Gecko/20100101 Firefox/152.0

Steps to reproduce:

Set DontCheckDefaultBrowser to true in policy (and verified via about:policy)
Open Firefox Settings, the Account & Sync still allows changing the default browser via "Psst, Firefox isn’t your default"

Actual results:

Account & Sync still allows changing the default browser via "Psst, Firefox isn’t your default"

Expected results:

The Default Browser should not be allowed to change.

Comment 1

[edward]

Attachment: Screenshot 2026-07-01 at 13.57.15.png

Comment 2

[BugBot [:suhaib / :marco]]

The Bugbug bot thinks this bug should belong to the 'Firefox::Sync' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 3

[Mike Kaply [:mkaply]]

I actually looked into this, and this policy never prevented the user from changing the default browser.

It prevented Firefox from showing a popup at startup asking about changing the browser

I don't disagree that we should offer that, but that's not what this policy is for.

Comment 4

[Mike Kaply [:mkaply]]

https://chromeenterprise.google/policies/#DefaultBrowserSettingEnabled is the Chrome policy.

Comment 5

[BugBot [:suhaib / :marco]]

The severity field is not set for this bug.
:mkaply, could you have a look please?

For more information, please visit BugBot documentation.

Comment 6

[Mike Kaply [:mkaply]]

Attachment: Bug 2051921 - Add policy for controlling default browser in prefs. r?bsmth

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/6216cc237ddb
https://hg.mozilla.org/integration/autoland/rev/7907f6a70190
Add policy for controlling default browser in prefs. r=bsmth,fluent-reviewers,akulyk,bolsson

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/7032bedb920a
https://hg.mozilla.org/integration/autoland/rev/9ca2e898060f
Revert "Bug 2051921 - Add policy for controlling default browser in prefs. r=bsmth,fluent-reviewers,akulyk,bolsson" for causing lint failures @ Policies.sys

Comment 9

[Sandor Molnar[:smolnar]]

Backed out for causing lint failures @ Policies.sys

Backout link: https://hg.mozilla.org/integration/autoland/rev/9ca2e898060fe791ea9be24955d664b07f34bd85

Push with failures

Failures log ->TEST-UNEXPECTED-ERROR | /builds/worker/checkouts/gecko/browser/components/enterprisepolicies/Policies.sys.mjs:964:9 | 'setAndLockPref' is not defined. (no-undef)

Comment 10

[Sandor Molnar[:smolnar]]

also these xpc failures

Comment 11

[Mike Kaply [:mkaply]]

Tree changes out from under me and I didn't rebase. Doh!

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/baafc37f84ac
https://hg.mozilla.org/integration/autoland/rev/70d5ecf0f27a
Add policy for controlling default browser in prefs. r=bsmth,fluent-reviewers,akulyk,bolsson

Comment 13

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/70d5ecf0f27a

Comment 14

[YUKI "Piro" Hiroshi]

We were able to disallow users to set Firefox as the default browser with setting pref.general.disable_button.default_browser to true (via Preferences policy or MCD) in enterprise use. The ability looks to be lost in Firefox 153 (the next ESR). Is there any chance to uplift the patch to the 153 branch?

Comment 15

[Mike Kaply [:mkaply]]

1. Yes, this will be uplifted to Firefox 153.
2. Forgot about pref.general.disable_button.default_browser. I'll make it work and get it uplifted.

Opened https://bugzilla.mozilla.org/show_bug.cgi?id=2055887

Comment 16

[Mike Kaply [:mkaply]]

Attachment: Bug 2051921 - Add policy for controlling default browser in prefs.

Original Revision: https://phabricator.services.mozilla.com/D311372

Comment 17

[Phabricator Automation]

firefox-esr153 Uplift Approval Request

• User impact if declined/Reason for urgency: Parity with Firefox 154/Policy
• Code covered by automated testing?: yes
• Fix verified in Nightly?: yes
• Needs manual QE testing?: no
• Steps to reproduce for manual QE testing:
• Risk associated with taking this patch: low
• Explanation of risk level: Policy only.
• String changes made/needed?: Yes, but for policy, we don't worry about English only.
• Is Android affected?: no

Comment 18

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-esr153/rev/836c907751be

Comment 19

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-esr153/rev/968bc90a28c4

Comment 20

[Brian Thomas Smith [:bsmth]]

Attachment: Bug 2051921 - Add ESR compat info for DefaultBrowserSettingEnabled. r=mkaply

Comment 21

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/73156ef55d9a
https://hg.mozilla.org/integration/autoland/rev/81a82229c31e
Add ESR compat info for DefaultBrowserSettingEnabled. r=mkaply DONTBUILD