Do I need to restart Apache after changing the php.ini file?

That depends on the SAPI you're using. If you're using PHP as an Apache module for example, you need to restart apache so that the php.ini values take effect.

If you're using FCGI, you need to restart the FCGI daemon for the PHP script that you want to see the values changed. Compare with

• Trouble changing upload_max_filesize on nginx

Depends, actually. Depends on how you use php inside that webserver:

• using php as module inside the http server: you have to restart the http server process
• using php as cgi backend: you do not have to restart the http server process or anything else
• using php fastcgi: you have to restart the fastcgi daemon, not the http server
• using php-fpm: you have to restart the fpm server process, not the http server process

It depends on what OS and version you are running.

I am running Apache/2.4.29 under Ubuntu.

PHP Version 7.2.24.

I restart apache with the following command and the restart is needed after modifying the php.ini file:

sudo service apache2 restart

On Debian 8 I had to restart PHP-FPM (and Apache) The above answers are correct, but here are the commands so you won't have to googling them.

Restart Apache :

/etc/init.d/apache2 restart

Restart php5-fpm :

sudo service php5-fpm restart