phpstan/extension-installer contains a Composer plugin which is blocked by your allow-plugins config. You may add it to the list if you consider it safe. You can run "composer config --no-plugins allow-plugins.phpstan/extension-installer [true|false]" to enable it (true) or disable it explicitly and suppress this exception (false) See https://getcomposer.org/allow-plugins

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Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires php ^8.1 but your php version (8.0.30) does not satisfy that requirement. Problem 2 - Root composer.json requires symfony/http-foundation ^6.4.0 -> satisfiable by symfony/http-foundation[v6.4.0, ..., v6.4.10]. - symfony/http-foundation[v6.4.0, ..., v6.4.10] require php >=8.1 -> your php version (8.0.30) does not satisfy that requirement. Problem 3 - simplesamlphp/simplesamlphp[v2.2.0, ..., v2.2.2] require php ^8.1 -> your php version (8.0.30) does not satisfy that requirement. - Root composer.json requires simplesamlphp/simplesamlphp ^2.2.0 -> satisfiable by simplesamlphp/simplesamlphp[v2.2.0, v2.2.1, v2.2.2].