After upgrading to PHP7.2 php-fpm was running as the _www user. PHP worked, but was unable to write to most files.
Needed to change php-fpm to use my own Mac user and group. Biggest difficulty was finding where my actual version of Apache & PHP are configured and where error logs are written. This is due to Homebrew adding to the native installs.
Try these paths if it happens again.
(May not be correct as I tried a lot of things to get this fixed)
Apache
Config /usr/local/Cellar/httpd24/2.4.27
Logs /usr/local/var/log/apache2
(Defined in /usr/local/etc/apache2/2.4/)PHP
/usr/local/etc/php/7.2/php-fpm.d