You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy

I need to update my password in my primary email account that goes back to 2006 (!) All my other gmail accounts work...just not this one. HELP

"You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy for keeping apps secure.

You can let the app developer know that this app doesn't comply with one or more Google validation rules."