[Affected versions]:

• 68.0b8
• 69.0a1 (2019-06-07)

[Affected platforms]:

• Win 8.1

[Steps to reproduce]:

1. Open Firefox
2. Right click on the Firefox icon inside the taskbar
3. Choose the Pin this program to taskbar option
4. Repeat several time, toggling between Pin this program to taskbar option/Unpin this program from taskbar options

Note: Sometimes I can trigger this issue only if after step 3 I do some browser navigation

[Expected result]:

• The Unpin this program from taskbar/ Pin this program to taskbar options should be shown alternative if activated.

[Actual result]:

• Pin this program to taskbar gets stuck after is toggled several times.

[Regression range]:

• I will provide one asap.

[Additional Notes]:

• On Windows 10 I can toggle this option only two times, then a singular “Close window” option appears.

I can't seem to reproduce this, either the Windows 8.1 version in the STR, or the Windows 10 version mentioned at the end. I'm suspicious that we might be seeing a bug in the taskbar itself.

Would you be able to capture a screen recording, so I can make sure I'm understanding what you're doing correctly?

Thanks. I am still having no luck reproducing this, and I kind of have to think it's a bug in the taskbar. There's only one thing I can really think of that might be relevant: what's the content of the %AppData%\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar directory after this bug occurs? Specifically, are there multiple copies of the Firefox shortcut in there?

Oh, I see now the problem.. I can reproduce this issue only by running firefox.exe from an unzip. Beta/Nightly version, not with a Full installer/Stub installer one.

(In reply to Matt Howell (he/him) [:mhowell] from comment #3)
what's the content of the %AppData%\Microsoft\Internet Explorer\Quick Launch\User Pinned\TaskBar directory after this bug occurs? Specifically, are there multiple copies of the Firefox shortcut in there?

• no Firefox shortcut is displayed, once the issue is triggered

I can reproduce this issue on WIndows 10 x64 (1809). No matter what version of Firefox I'm using, I will get different icons when pinned, and after right clicking twice on the icon, will get that following string like in the attachment, and pin to taskbar will eventually not work.

The folder taskbar (the path in Comment 3) is clean on the system, and no other instance of Firefox is installed.

Thanks for the additional info, that's very helpful. It's also completely fascinating, I've never seen anything at all like that. I still think this is more likely to be a bug in the taskbar than it is to be our bug. My guess is that it's somehow confusing some existing start menu shortcuts to other copies of firefox.exe with the shortcut file that's created when you make a taskbar pin. I suppose that's possible because that shortcut doesn't have the right app ID in it like the ones the installer creates do (since this is from a zip build where the installer wasn't run), but I'm totally guessing.

I'm moving this bug out of the Installer component, since if it reproduces from a zip build that means the installer can't be involved.

This issue is not a regression. I can reproduce it way back to Fx 40.0a1. Conclusions on older builds are irrelevant since the FX icon disappears completely.

Did encounter this issue on Windows 10 (v1909) with Firefox 74.0b9, while pinning and unpinning in taskbar a couple of times.