I’m not entirely sure what you mean by “non-virtual” environment.
I had a somewhat similar problem with a remote server that I resolved by restarting the php-fpm service on the server. In your case, you’d do that by vagrant sshing into your VM, and running commands that look kind of like this:
sudo service php7.1-fpm stop
# some output...
sudo service php7.2-fpm start
# some more output...