Thank you for your summary.

For the two setups I have that will run QB Desktop 2021 at this time:

One is a desktop machine where I replaced the hard drive and started with a fresh install of Windows 10 about a year ago, and that included both Edge and Internet Explorer because I know that I did not install Internet Explorer myself.

The second is a laptop running Win 8.1 for about six years. It will run 19, 20, and 21 of QB Pro, Premier, and Enterprise.

I don't use any connected features except for Intuit merchant services.

When I search the internet for the availability of Internet Explorer in Windows 10, two top replies, one from March of this year from an independent support site and another site from this month from Microsoft confirm it is included in Windows 10.

It seems to be the case that the older installation files for Windows 10 include IE 11 embedded in it. I was able to open an IE 11 window in Windows 10 using the first paragraph of instructions below. I can't speak regarding the newest Windows 10 installations.

Microsoft confirms it is included in Windows 10, with a caveat that you may need to load it as a feature. See second paragraph of instructions. I do recall an earlier post from someone saying they were unsuccessful loading it as a feature, but others may have greater success with it.

Use Internet Explorer in Windows 10

To open Internet Explorer 11, select Start , and enter Internet Explorer in Search . Select Internet Explorer (Desktop app) from the results.

If you can't find Internet Explorer on your device, you'll need to add it as a feature. Select Start > Search , and enter Windows features. Select Turn Windows features on or off from the results and make sure the box next to Internet Explorer 11 is selected. Select OK, and restart your device.