How to solve a catch 22 situation trying to upgrade an old 2009 mac mini to El Capitan with an AppleID created in 2019? I had the chance to have in my hands an old mac mini from 2009. I turned it on, it works perfectly. Currently it runs Mac OS X 10.6.8.

Now, I would like to try to upgrade it to a slightly newer version, like El Capitan.

So, I created a brand new AppleID on https://appleid.apple.com with all my data, including a valid credit card. I checked and Apple did registered and then deleted a transaction with a small amount, to check the credit card. I also confirmed my email using the code Apple sent me during the AppleID registration phase.

After that I opened the "App Store" app on this old Mac, I navigated to the page where I can download El Capitan from, and a pop up asks me to input my AppleID credentials. 

I've done it and a pop up tells me that my AppleID have not yet been used in the app store and that I have to verify it.

I click on "verify" and a second pop up tells me I have to update the software and the OS to be able to verify my AppleID.

So I'm now stuck in this catch 22 situation.

Can someone explain me if there's a way to solve it?

Cheers.
here's how I fixed that situation.


I downloaded Apple Music on my Android phone.
I start the procedure to subscribe to the service with my existing AppleID.
As it happened in my old Mac Mini, Apple Music on Android opened a popup saying my AppleID had not yet been verified.
On Android, however, in contrast with the Mac Mini, the verification link worked.
I had to retype the details of my credit card that I had already provided when I created the AppleID for the first time.
The verification process completed successfully, Apple debited my credit card for the second time, cancelling the payment after a while.
After that, I accessed the Apple Store from the old Mini Mac with the AppleID I had just verified on Android and...
It worked flawlessly. I downloaded OS X El Capitan and completed the upgrade successfully.


I write this procedure in case someone else will get stuck in the same, even highly unlikely, situation.