How to upgrade PHP composer on a Plesk server

1. Connect to the server via SSH

2. Check what version is currently used:

   Note: replace X.X with the current PHP version and <Version> with the desired composer version.

   # /opt/plesk/php/X.X/bin/php /usr/lib64/plesk-9.0/composer.phar --version

3. Update or downgrade to the specified version:

   # /opt/plesk/php/X.X/bin/php /usr/lib64/plesk-9.0/composer.phar self-update <Version>

   Note: In case the command above does not work, use the below one:
   /opt/plesk/php/X.X/bin/php /usr/local/psa/var/modules/composer/composer.phar selfupdate --2

For example:

# /opt/plesk/php/7.3/bin/php /usr/lib64/plesk-9.0/composer.phar self-update 2.0.8
Upgrading to version 2.0.8 (stable channel).

1. Connect to the server via SSH

2. Check what version is currently used:

   Note: replace X.X with the current PHP version and <Version> with the desired composer version.

   # /opt/plesk/php/X.X/bin/php /usr/lib/plesk-9.0/composer.phar --version

3. Update or downgrade to the specified version:

   # /opt/plesk/php/X.X/bin/php /usr/lib/plesk-9.0/composer.phar self-update <Version>

   Note: In case the command above does not work, use the below one:
   /opt/plesk/php/X.X/bin/php /usr/local/psa/var/modules/composer/composer.phar selfupdate --2

For example:

# /opt/plesk/php/7.3/bin/php /usr/lib/plesk-9.0/composer.phar self-update 2.0.8
Upgrading to version 2.0.8 (stable channel).