php GD library error in ubuntu

Yeah. Just try:

sudo apt-get install php5-gd

You probably will have to remove the offending line in your php.ini, either in php.ini or in /etc/php5/conf.d/gd.ini maybe.

Probably something like

sudo apt-get install php-gd

should do it, if not try

apt-cache search php | grep gd

sudo apt install php-gd will work but the thing is it will download the plugin for the latest PHP version.

If your PHP version is not the latest, then you can add version in it:

# PHP 7.1
sudo apt install php7.1-gd

# PHP 7.2:
sudo apt install php7.2-gd

# PHP 7.3
sudo apt install php7.3-gd

# PHP 7.4 (latest)
sudo apt install php-gd

For me the solution was:

locate --regex /mcrypt[.]so\$ /gd[.]so\$ /suhosin[.]so\$ /pdo_mysql.so\$ /pdo[.]so /mysqli[.]so\$ '/php5/.*/mysql[.]so$'

Which returned the location of all the libraries that my php5 install was having trouble finding:

/usr/lib/php5/20090626+lfs/gd.so
/usr/lib/php5/20090626+lfs/mcrypt.so
/usr/lib/php5/20090626+lfs/mysql.so
/usr/lib/php5/20090626+lfs/mysqli.so
/usr/lib/php5/20090626+lfs/pdo.so
/usr/lib/php5/20090626+lfs/pdo_mysql.so

I was a little worried that these look they might be old versions, but I used their paths anyway. Stefgosselin identified the location of the ini files, /etc/php5/conf.d/. I modified them all. The command below will modify all of the *.ini files there, so make sure all of yours really need modifying. Obviously you need to use the target path you discovered with the locate command in place of mine, /usr/lib/php5/20090626+lfs/:

 sudo sed -ri -e "s|^(extension=)(\w{2,10}[.]so)$|\1/usr/lib/php5/20090626+lfs/\2|g" /etc/php5/conf.d/*.ini

Before finding this solution I tried several apt-get purge and apt-get reinstall commands without luck. I'm not sure, but my problem may have originated with installation of zend from source or phpmyadmin with aptitude. It never caused any php errors, just the annoying warning you mentioned. Finally php5 can launch without errors:

php5 --version

gives ...

PHP 5.3.5-1ubuntu7.2 with Suhosin-Patch (cli) (built: May  2 2011 23:18:30)  Copyright (c) 1997-2009 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies
    with Suhosin v0.9.32.1, Copyright (c) 2007-2010, by SektionEins GmbH