The Apple ID you entered couldn't be found...

[BollywooD]

I get this error when trying to upgrade any apps in the Mac App Store since upgrading to Sierra:
"The Apple ID you entered couldn't be found or your password was incorrect. Please try again."

I've tried signing out/in to Mac App Store, restarting my Air.
does anyone have any suggestions...

thanks in advance

 

[BollywooD]

so I reset my AppleID password and restarted a couple of times, and now its working.