Downgrading PHP 7.1 to 7.0

@KEEVITAJA have you fixed your problem?

I have tried it. Just follow below.

sudo apt-get install php7.0-fpm php7.0-mysql php7.0-curl php7.0-mcrypt php7.0-xml php7.0-mbstring
 
sudo apt-get install php7.0-gd

Edit each site nginx configuration in Forge, replace the fastcgi_pass path to the 7.0 equivalent.
Edit /etc/php/7.0/fpm/pool.d/www.conf, change the "user" and "group" to forge. 

Also change listen.mode = 0666.

sudo update-alternatives --set php /usr/bin/php7.0      == to change the php version

sudo service nginx restart
sudo service php7.0-fpm restart

 
Note this won't affect the php-cli version either which may cause issues, I haven't figured how to change that over yet.
TBH if you can just reprovision the server I would do that, if someone can point to exact provisioning info performed by Forge that would make the switch easier.
Alternatively allowing the new upgrade tool to downgrade versions as well...

And also follow this reference "https://www.digitalocean.com/community/tutorials/how-to-upgrade-to-php-7-on-ubuntu-14-04" after "Updating Nginx Site(s) to Use New Socket Path" section

I hope it helps and will work on your end :)

I have not fixed the issue. I have bunch of stuff running there and i do not want to mess everything up.

But another question is, when you create a new site with forge, will it be 7.0 or 7.1?