Update 2021-01-05: On Catalina: You only start from step 3 and skip step 6 because PHP7 is already installed.
Update 2018-10-18: The same method works with macOS 10.13 High Sierra.

After I updated my laptop macOS from High Sierra to Mojave, Apache with PHP stopped working properly, which I discovered to be a common problem with Mac users, and it wasn’t only me.

I tried to check for solutions online, but all of them were complicated to apply, that’s why I list here very simple steps using Terminal to solve the problem:

1. Start by installing Homebrew if you don’t have it already ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
2. Install PHP by using brew install [email protected] This will install PHP version 7.1, and the php.ini file would be located in: /usr/local/etc/php/7.1/php.ini
3. Open Apache config by running: sudo nano /etc/apache2/httpd.conf
4. Press CTRL + W on your keyboard to search within the file, locate the following line and uncomment it by removing the # sign from the beginning of the line. LoadModule php7_module /usr/local/opt/[email protected]/lib/httpd/modules/libphp7.so
5. You need to configure the directory indexes to accept PHP files, search for the line

<IfModule dir_module>
    DirectoryIndex index.html
</IfModule>

and replace it with the following lines:

<IfModule dir_module>
    DirectoryIndex index.php index.html
</IfModule>
<FilesMatch \.php$>
    SetHandler application/x-httpd-php
</FilesMatch>

1. Start PHP by using brew services start [email protected]
2. Restart Apache by using sudo /usr/sbin/apachectl restart

And you’ll be done with PHP and Apache working again.