[InvalidArgumentException] Command "self-update" is not defined.

The solution for this is noted below

[InvalidArgumentException] Command “self-update” is not defined.

Solution

sudo apt-get remove composer

php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php -r "if (hash_file('sha384', 'composer-setup.php') === '8a6138e2a05a8c28539c9f0fb361159823655d7ad2deecb371b04a83966c61223adc522b0189079e3e9e277cd72b8897') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
php composer-setup.php
php -r "unlink('composer-setup.php');"

sudo mv composer.phar /usr/local/bin/composer

Try other methods by searching on the site. That is if this doesn’t work