[PHP] Exception: Call to undefined function curl_init()

Today I ran into a trap while maintaining an old PHP Codeigniter project on an ubuntu server, the error message says:

Severity: error --> Exception: Call to undefined function curl_init()

Turns out this is very easy to fix, we just need to install the missing CURL extension for PHP.

Solution

To locate where the Apache’s ROOT configuration directory

apache2ctl -V | grep HTTPD_ROOT

The result in my case is

-D HTTPD_ROOT="/etc/apache2"

Just so we know the ROOT directory is /etc/apache2, and let’s check the mods-enabled directory in it:

ls /etc/apache2/mods-enabled/ | grep php

The result in my case is

php7.4.conf
php7.4.load

Now we confirm that we’re running php7.4 here.

sudo apt install php7.4-curl

To check the installation by running the command:

php7.4 -r "curl_init();"

It returns nothing if we’re all good, otherwise, an error message will be shown like below:

PHP Fatal error:  Uncaught Error: Call to undefined function curl_init() in Command line code:1

Lastly, don’t forget to restart apache2 service:

sudo service apache2 restart