"unable to download app" big sur notification

This confirms exactly what I am seeing. For me, the app is the Steelseries Nimbus Companion App.

This started last month and the notification would return every time the Mac was unlocked (i.e. many, many time a day). After a week, a second notification join it. Exactly the same except for the date/time shown. This eventually stopped (no idea why) but has come back today. I expect to see a second one join it next week.

One thing I have not tried yet is rebooting my Mac. There is an update to install, so I will try that now. It may delay the problem reappearing for a few days.

(As an aside, as it may be related, I have downloaded an Arcade app from the store and after the download completed, the Get button returned, not a Play button. The app will not launch.)

I have been getting this as well. My guess is that it's related to the ability of M1 macs to run iOS apps and App Store preferences.

I am running Big Sur on an Intel Macbook which does not support iOS apps

When I have the option App Store > Preferences > "Automatically download apps purchased on other devices" enabled and I purchase a new iOS app via the App Store on my phone, I get a few notifications on MacOS for a few different iOS apps stating they can't be downloaded. These are not necessarily for the app I've just purchased on iOS, I think any purchase simply triggers them again. I assume they are apps that have opted in to support being run on M1 macs.

When I have the option App Store > Preferences > "Automatically download apps purchased on other devices" disabled and I purchase a new app via iOS, I do not get notifications in MacOS.

Re-enabling this option, and purchasing a new app, I get the notifications again.

I imagine it's a bug that will be fixed at some point. In the meantime, the work around seems to be to disable that option (that's what I've done).

Note: I'm currently running MacOS 11.1, but looked through the 11.2 changelog and don't see mention of this particular issue so I suspect it's still present and Gary Makin's comment above I assume is related to updating to 11.2.

If I was going to suggest a reason for the problem, it would be exactly what you have described.

Unfortunately, turning off the option only impacts apps purchased afterwards. The existing notification continues to return, even after a reboot.

It is sad that such simple bugs are escaping into the wild. This should have been caught and fixed in beta testing.

Yes, I am on 11.2 now.

I have found something that makes as a difference.

I have been dismissing the notification with a swipe to the right. But, when I used the close button that appears over the top left corner, the notification does not come back when the screen is unlocked.

From its past behaviour, I expect the notification will eventually return but perhaps once a week, not many times a day.

A reboot did not help.