@ClicShopping,
Thank you for your work.
I make in the past some upgrade,
The first it was not simple, but at the end, no problem if you follow the best pratices.
Just you must do be careful about the template. If you use the default template, take a tool like Beyong Compare and look the files.
if you have your own template, just push the files and update your template
I think this is the first part you must do.
Newbie to a newbie !