do you have PHP intl extension installed? This is required to use NumberFormatter as well as all of the other classes in the link. Also, you can set all of your formatting in your config file so you don’t have to do it everywhere.
Have you tried restarting your machine? I use ampps as well and sometimes have to restart because it will not restart properly. I installed the intl ext. in the control panel as normal and it worked for me.
v 2.5 (& 2.8 on differnt machine)
I had some issues with mongo and php so i can’t use the latest versions with ampps
Did it actually install the extension? You can quickly check all of your extensions by using the following: