Theme Changes from 3.8 to 4.0

Hi,
I am planning to upgrade my nopcommerce site to 4.0 from 3.8 .

Is there any article or guide to show what changes needs to be made to the themes?

Or can i use a 3.8(or even 3.90) theme on a 4.0 site?

If i cannot, what changes do i need to make?

BR

You can not use nopcommerce3.8 or 3.9 theme directly at nopcommerce4.0 as the folder structure changes and some view  also moved and theme.config change to theme.json.

Now if you want to update the current theme for the nopcommerce4.0 it will be good to see the folder structure and view of default clean nopcommerce4.0 and update accordingly.