I have just made a test upgrade and it finished flawless in 10 minutes.

Everything seemed to be fine but I realised that there was something wrong with default page.

On my prod site default page is

http://prodsite.com/page/index.html

when I set Pages as default Application the page is redirected to

http://testsite.com/index.php/page/index.html

/page/index.html seems to be coming from upgrade and I could not find how to correct it.

And one more thing Where is the profile picture setting for square pictures instead of circular ones ?

The problem turned out to be an Explorer cache problem. Solved after clearing the cache but still unable to find the profile Picture setting for square profile pictures.

I remember I had read a topic about this but search did not help..

You can change it in Customization - Themes - Edit the default theme (click on pencil) -  go to Custom tab and uncheck Use rounded photos. 

Hope it helps  

Thanks ‌@‌Tanja I really did not think the option would be inside the theme, where it now seems obvious it would be there.. Only looked in members and General config