mozilla-mobile/firefox-ios

If closing a background tab while a new URL is being loaded from a bookmark, the new URL stops loading

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#32334 opened on Mar 1, 2026

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Bug 🐞Contributor OKGood first issue

Description

Steps to reproduce

  1. Open a tab and load any website
  2. Open a new blank tab
  3. From the blank tab, load any URL from a bookmark
  4. While the new URL is waiting on a response to the initial HTTP request, close the first tab

Expected behavior

The first tab is closed while the second tab continues loading.

Actual behavior

The first tab is closed and the second tab stops loading and returns to the homepage.

Note that this only happens if I close the first tab while the initial HTTP request is pending in the second tab. If the initial request succeeds and it’s just waiting on other assets like images and fonts, the issue won’t occur. You have to get it at a very specific time.

Device & build information

  • Device: iPad Air 2019 A2163 / iOS 26.3
  • Build version: 68216
  • First seen version: Not sure

Notes

Attachments:

:information_source: Reference Person

@Foxbolts

┆Issue is synchronized with this Jira Task

Contributor guide

Tech stack
swiftios
Domain
mobile
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
SwiftiOS developmentHTTP request lifecycleTab management
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Investigate the tab lifecycle and network request cancellation logic in Firefox iOS. Look at how the browser handles tab closure and cancels pending requests. Focus on the code that manages tab switching and request delegation. The issue suggests that closing one tab interrupts an in flight HTTP request in another tab. Examine the `TabManager` and `WebView` classes, particularly how they handle `WKNavigationDelegate` callbacks and request cancellation when tabs are removed. The provided log file and screen recording should help identify the exact timing and sequence of events.