• Fatal error: Allowed memory size of 123456 bytes exhausted (tried to allocate 234567 bytes) in /path/file.php

Usually your php.ini will be located at (XX – PHP version, for example 73):

vi /usr/local/php73/lib/php.ini

or use below trick to find your php.ini would be to ask php itself what it’s using, eg:

/usr/local/bin/php --ini | grep 'Loaded Configuration File'

or another trick to find php.ini

php -i | grep "php.ini"

Now open the php.ini file and edit memory_limit to a higher value.

memory_limit = 8M      ; Maximum amount of memory a script may consume (8MB)

Save, and then restart apache.

systemctl start httpd.service

CentOS/RHEL (Red Hat) Linux version 7.x or newer specific commands

or

sudo systemctl restart httpd.service 

Alternative way: php.ini per folder

Location of the global server php.ini file is

/usr/local/php/php.ini

Location of the global per account php.ini file is

/home/USERNAME/php.ini

You can also have per folder changes, example:

/home/USERNAME/public_html/website1.com/php.ini
/home/USERNAME/public_html/website2.com/php.ini
/home/USERNAME/public_html/website2.com/myapp/php.ini

How to test php.ini changes?
Simple create phpinfo.php file in the users public_html folder and add the following content in it.

Example location: /home/USERNAME/public_html/phpinfo.php

<?php
phpinfo();
?>

Now open url in your browser (Apache restart is NOT needed):

http://your-domain.com/phpinfo.php

PHP.ini values

http://php.net/manual/en/ini.list.php