Problem

When you create a website, it error.

Error: Please allow extension : json

Reason

RVsitebuilder requires PHP extension "json" to enable but it's disabled for your domain name.

Solution

Just simply enable PHP extension for alt-php (CloudLinux)

1. Login to your cPanel
2. Go to PHP Selector | extensions feature (If this feature doesn't available on your cPanel account, please ask your hosting provider to enable this function)
3. Select "json" extension

4. Go back to RVsitebuilder 7 to create site again.