1967825 - Incorrect back navigation behavior in PWA

Status: VERIFIED FIXED

(Firefox for Android :: Browser Engine, defect, P2)

Description

[Markus Stange [:mstange]]

This is a recent regression.

Steps to reproduce:

1. In Firefox for Android, go to https://mastodon.social/ .
2. Install it as a PWA by selecting "Add app to Home screen" in the Firefox menu.
3. Go to the home screen.
4. Open the PWA by tapping on the new icon.
5. Press the Android back button or execute the Android back swipe gesture.

Expected results:
The PWA should disappear and the home screen should appear.

Actual results:
Firefox remains open and navigates "back" to an empty dark gray screen. There is no way to go forward. If you now go to the home screen manually and tap the PWA again, you go back to the dark gray screen.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

This bug has been marked as a regression. Setting status flag for Nightly to affected.

Comment 2

[Markus Stange [:mstange]]

[Tracking Requested - why for this release]: Regression which temporarily breaks the UI

Regression range: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=0fd4c5364227&tochange=3cde666e7966

(I used mozregression until I got this mozilla-central range from Nightlies, and then manually installed Fenix builds from autoland. This took a lot more time than it needed to; fixing mozregression to properly support Fenix would make this process a lot less painful. See bug 1857026 + bug 1969327 + bug 1969329.)

Likely suspect: bug 1961852

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

:royang, since you are the author of the regressor, bug 1961852, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 4

[Roger Yang [:royang]]

Thanks for chasing this down. I will investigate.

Comment 5

[Roger Yang [:royang]]

Confirmed reproducible. And by checking out the build right before the regressor, the issue is fixed.

Comment 6

[Roger Yang [:royang]]

Issue caused by removal of onBackPressed override by mistake. I will restore as fix.

Comment 7

[Roger Yang [:royang]]

Attachment: Bug 1967825 - Restore PWA onBackPressed handling that was incorrectly removed.

Comment 8

[Roger Yang [:royang]]

Attachment: Bug 1967825 - Restore PWA onBackPressed handling that was incorrectly removed.

Original Revision: https://phabricator.services.mozilla.com/D251769

Comment 9

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined: In PWA if the user tries to back out of the app they will get stuck in a blank screen
• Code covered by automated testing: no
• Fix verified in Nightly: no
• Needs manual QE test: no
• Steps to reproduce for manual QE testing: Open a PWA shortcut from Android Home and try to back out through either gesture or Android OS back button.
• Risk associated with taking this patch: Low risk
• Explanation of risk level: This is restoring a portion of the code that was accidently removed.
• String changes made/needed: None
• Is Android affected?: yes

Comment 10

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/02ba7ada484e

Comment 11

[Markus Stange [:mstange]]

(In reply to Roger Yang [:royang] from comment #4)

Thanks for chasing this down.

Thanks for the quick fix!

Comment 12

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/47feb4a104b1
https://hg.mozilla.org/releases/mozilla-beta/rev/5408cdc92fc6

Comment 13

[Vasilica Tamas QA [:vtamas]]

Attachment: Recording_20250603_173809.mp4

This issue is verified as fixed on Firefox for android Nightly 141 (2025-06-02), Firefox 140 beta 4 and using Google Pixel 8 with Android 15. Confirming that the PWA shortcut is dismissed when tapping on system back button.