I have Windows, without iTunes, so naturally those links do not work on my PC.

When I check the Web Console in that tab, I find:

Prevented navigation to “itmss://apps.apple.com/us/app/macos-catalina/id1466841314?mt=12&ign-mscache=1” due to an unknown protocol.

You could check for that same message -- you can open the Web Console in the lower part of the tab using either:

• "3-bar" menu button > Web Developer > Web Console
• (menu bar) Tools > Web Developer > Web Console
• (Mac) Command+Alt+k

Assuming yours mentions the same issue, I guess we need to figure out a way for Firefox to properly hand off itmss: links to iTunes. That seems like it should be automatic on Mac, but apparently there's a disconnect on your Firefox for some reason. ??

FWIW, it's not just my Firefox. It's Firefox running on anyone's Mac on any version of macOS. Checking the first link, I see… "Some cookies are misusing the recommended “SameSite“ attribute" When I click on one of the download links, it opens this tab… https://apps.apple.com/us/app/macos-catalina/id1466841314?mt=12 and I see… This page uses the non standard property “zoom”. Consider using calc() in the relevant property values, or using “transform” along with “transform-origin: 0 0”.

I haven't a clue what any of it means. :)

I don't see the same message.

From the first tab… https://support.apple.com/en-us/HT211683 I see: "Some cookies are misusing the recommended “SameSite“ attribute" When I click on one of the download links it opens this tab… https://apps.apple.com/us/app/macos-catalina/id1466841314?mt=12 and I see: "This page uses the non standard property “zoom”. Consider using calc() in the relevant property values, or using “transform” along with “transform-origin: 0 0”."

FWIW, it's not just me. All users running Firefox on Macs have the same problem. I volunteer on ASC and we all have to tell users not to use Firefox to download from the page.

Sorry, I didn't mention that you need to break links in replies to avoid your post going into the spam moderation queue. Oh well, we'll get it eventually!

What if you edit the address in the address bar from starting with https:// to starting with itmss:// and press Return to submit that. Does Firefox ask about launching iTunes or does it say it doesn't know what to do with itmss:// links?

If Firefox understands the protocol, I would expect to get something like the following dialogs Firefox displays for zoommtg:// links (if you installed the Zoom client software):

"Sorry, I didn't mention that you need to break links in replies to avoid your post going into the spam moderation queue."

Now you tell me. :)

I think it would be easiest for all concerned if someone on a Mac could investigate the issue. Firefox does indeed open a similar dialog window asking what to use. When you select the App Store, the App Store does open but it refuses to connect.

Okay, so the problem is not that the App Store doesn't open; it opens. The problem is that for some reason, the App Store does not retrieve the linked item.

Maybe Firefox isn't sharing the link properly, or something else is happening. I agree. I can't debug that hand-off.

It's not super critical of course. Users can always use Safari for the links. Any browser that uses WebKit I suppose. I was just hoping to avoid telling Mac users not to use Firefox for the links but there may not be a solution.

Thank you for the help nonetheless.

I see this warning in the Web Console. Prevented navigation to “itmss://apps.apple.com/us/app/macos-catalina/id1466841314?mt=12&ign-mscache=1” due to an unknown protocol.

Okay, so the problem is not that the App Store doesn't open; it opens. The problem is that for some reason, the App Store does not retrieve the linked item. Maybe Firefox isn't sharing the link properly, or something else is happening. I agree. I can't debug that hand-off.

Found out something really bizarre. Turns out it's possible to use Firefox to download the Catalina, Mojave and High Sierra links on M1 Macs. Which shouldn't be possible at all since M1 Macs ship with Big Sur.

It's all very strange.