Firefox taskbar options are gone in Windows 10, how to fix?

I have the Mozilla Firefox pinned to taskbar in Windows 10. Right-clicking the taskbar icon should bring some options like:

• Open new tab
• Open new window
• New private window

Suddenly, one day, I noticed these options were gone:

What might have caused this, and how to fix it?

I tried reinstalling Firefox, refreshing it, and even deleting the profile folder altogether from %appdata%, to no avail.

Solution 1:

What might have caused this?

Just another random bug, it seems. It might have been caused by restarting Windows while it was downloading updates, which is a lame excuse indeed but it’s the only thing I can think of.

How to fix it?

I found that this works:

1. Access about:config from the address bar.
2. Look for a setting called browser.taskbar.lists.enabled.
3. Double-click it to set its value to false
4. Double-click it again to (re)set its value to true, which is the default.

And now it’s fixed.