Message to install package

I keep getting a message appearing on my Arduino IDE interface saying,
"Install this package to use your Arduino/Genuino board".

Why? I have been using UNOs for a while.
Is there some information somewhere?

Which IDE version are you using? I ran into something like that a while back with my Pro Micro clone. I think it's supposed to be a system where the IDE recognizes the board when it's plugged in and then helps you install the hardware package for it. Of course there's not much point in telling you to install a package that's already installed, as I'm sure Arduino AVR Boards already is on your system. It was especially annoying with the Pro Micro because it reconnects after every upload and you keep getting new pop up notifications every time even if you already have one on the screen. It would end up being like 20 deep after a while and started making my system unstable. The problem seemed to go away at some point, I assumed this was because I had updated to a new IDE version that had the problem fixed but I don't use the Pro Micro much. I haven't encountered it with any other board.

I am using i.6.13.

How do I check if AVR Boards is loaded? I can't see it in libraries.

I experienced the issue while using one of the hourly builds, so I wasn't terribly surprised to encounter a strange issue with what seemed to be a new feature. It looks like this functionality was added in August:

Add Cloud API integration

This method discovers if a connected board needs an additional core and helps the user downloading it via BoardManager

But clearly there is something not working correctly with it.

vagulus:
How do I check if AVR Boards is loaded?

If the Arduino AVR Boards are showing up in the Tools > Board menu then it's installed. You could also check at
Tools > Board > Boards Manager, which will also show you which version you have installed.

vagulus:
I can't see it in libraries.

That's because it's not a library, it's a hardware package.

Yes. It's installed. Thanks.

However, that only makes it more confusing that I should get the message I mentioned.
Perhaps whoever sent it can explain for us.

Thanks