The command line help of composer outputs deprecation warnings. E.g. running composer --help on PHP 8.1 gives plenty of these: Deprecation Notice: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in /usr/share/php/Symfony/Component/Console/Descriptor/TextDescriptor.php:120 This file belongs to the package symfony-console. The current version in portage is 2.8.52, which is extremely old. Upstream's current version is 6.2.7.