Q: Hey Guys, I've just performed Mac OS upgrade to El Captain and I can not connect to APP Store and to my Itunes Account . Do you guys have an idea about what is going on ? I can not download, buy and update any file into my Macbook Pro. Many Thanks.

Hi lccrisci,

Thanks for the question.  Did you restart your Mac after the upgrade to OS X El Capitan finished?  If so, the next thing to try would be to sign out of your iTunes account on your Mac, restart the computer, then sign back in again to refresh.   While you are at it, this would be a good time to check your iTunes account billing information.  You may need to re-enter your credit card security code and expiration date.  Doing these two things should refresh the iTunes account.   

Mac App Store: Sign in and out

Change or remove your Apple ID payment information

If the issue persists, try these steps for connectivity issues with the iTunes Store:

If you can’t connect to the iTunes Store

Take care,