1621223 - Can’t exit Responsive Design Mode (TypeError: "can't access property "unwatchTargets", this.targetList is undefined")

Status: RESOLVED DUPLICATE of bug 1621316

(DevTools :: Responsive Design Mode, defect)

Description

[Chris Morgan]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:76.0) Gecko/20100101 Firefox/76.0

Steps to reproduce:

1. Enter Responsive Design Mode (e.g. with Ctrl+Shift+M).
2. Exit Responsive Design Mode (e.g. with Ctrl+Shift+M).

(If this succeeds, try again a few times, perhaps both slowly and quickly after entering—I’ve reproduced the defect half a dozen times, but have had it successfully exit once.)

Actual results:

It briefly switches the scrollbar style back to the regular non-overlay scrollbars, as though it were switching out, then they change back to the RDM overlay toolbars.

Nothing else happens. Further attempts to close RDM (Ctrl+Shift+M, the × button in the RDM toolbar, the RDM icon in the dev tools) do nothing at all (not even the scrollbar style switcheroo).

In the Browser Console, I see the following when I open RDM (uncertain whether it’s related):

[Exception... "Not implemented"  nsresult: "0x80004001 (NS_ERROR_NOT_IMPLEMENTED)"  location: "JS frame :: resource://gre/modules/RemoteWebNavigation.jsm :: get sessionHistory :: line 147"  data: no] RemoteWebNavigation.jsm:147:11
    get sessionHistory resource://gre/modules/RemoteWebNavigation.jsm:147
    construct chrome://global/content/elements/browser-custom-element.js:1249
    start resource://devtools/client/responsive/browser/tunnel.js:207
    start resource://devtools/client/responsive/browser/swap.js:281
    InterpretGeneratorResume self-hosted:1156
    AsyncFunctionNext self-hosted:695
    (Async: async)
    init resource://devtools/client/responsive/ui.js:191
    ResponsiveUI resource://devtools/client/responsive/ui.js:115
    openIfNeeded resource://devtools/client/responsive/manager.js:126
    toggle resource://devtools/client/responsive/manager.js:92
    onKeyShortcut resource://devtools/client/framework/devtools-browser.js:344
    onKey resource:///modules/DevToolsStartup.jsm:881
    xulKey resource:///modules/DevToolsStartup.jsm:805
    (Async: EventListener.handleEvent)
    createKey resource:///modules/DevToolsStartup.jsm:915
    attachKeys resource:///modules/DevToolsStartup.jsm:805
    hookKeyShortcuts resource:///modules/DevToolsStartup.jsm:777
    hookWindow resource:///modules/DevToolsStartup.jsm:509
    onWindowReady resource:///modules/DevToolsStartup.jsm:465
    onWindowReady self-hosted:879
    _delayedStartup chrome://browser/content/browser.js:2093
    _delayedStartup self-hosted:875
    (Async: EventListener.handleEvent)
    onLoad chrome://browser/content/browser.js:1878
    onLoad self-hosted:875
    (Async: EventHandlerNonNull)
    <anonymous> chrome://browser/content/browser.xhtml:120

… and when I exit RDM:

TypeError: "can't access property "unwatchTargets", this.targetList is undefined"
    destroy resource://devtools/client/responsive/ui.js:366
    closeIfNeeded resource://devtools/client/responsive/manager.js:196
    toggle resource://devtools/client/responsive/manager.js:92
    onKeyShortcut resource://devtools/client/framework/devtools-browser.js:344
    onKey resource:///modules/DevToolsStartup.jsm:881
    xulKey resource:///modules/DevToolsStartup.jsm:805
    createKey resource:///modules/DevToolsStartup.jsm:915
    attachKeys resource:///modules/DevToolsStartup.jsm:805
    hookKeyShortcuts resource:///modules/DevToolsStartup.jsm:777
    hookWindow resource:///modules/DevToolsStartup.jsm:509
    onWindowReady resource:///modules/DevToolsStartup.jsm:465
    _delayedStartup chrome://browser/content/browser.js:2093
    onLoad chrome://browser/content/browser.js:1878
    EventHandlerNonNull* chrome://browser/content/browser.xhtml:120

Expected results:

It should have exited Responsive Design Mode.

I believe this is a recent regression. The current nightly build is the first I’ve experienced it in, but I may not have entered Responsive Design Mode for two weeks.

Comment 1

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

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Micah [:mtigley] (she/her)]

Hello, thanks for filing! We have a duplicate of this issue in Bug 1621316 and are currently investigating. I'll mark this as a duplicate.