Your requirements could not be resolved to an installable set of packages. Problem 1 - vimeo/psalm[5.22.0, ..., 5.25.0] require nikic/php-parser ^4.16 -> satisfiable by nikic/php-parser[v4.16.0, ..., v4.19.1]. - You can only install one version of a package, so only one of these can be installed: nikic/php-parser[v4.13.2, ..., v4.19.1, v5.0.0, v5.0.1, v5.0.2, v5.1.0]. - vimeo/psalm[5.14.0, ..., 5.21.1] require sebastian/diff ^4.0 || ^5.0 -> satisfiable by sebastian/diff[4.0.0, ..., 4.0.6, 5.0.0, ..., 5.1.1]. - vimeo/psalm 4.30.0 requires sebastian/diff ^3.0 || ^4.0 -> satisfiable by sebastian/diff[3.0.0, ..., 3.0.6, 4.0.0, ..., 4.0.6]. - phpunit/php-code-coverage 11.0.5 requires nikic/php-parser ^5.0 -> satisfiable by nikic/php-parser[v5.0.0, v5.0.1, v5.0.2, v5.1.0]. - You can only install one version of a package, so only one of these can be installed: sebastian/diff[3.0.2, ..., 3.0.6, 4.0.0, ..., 4.0.6, 5.0.0, ..., 5.1.1, 6.0.0, 6.0.1, 6.0.2]. - phpunit/phpunit 11.2.7 requires phpunit/php-code-coverage ^11.0.5 -> satisfiable by phpunit/php-code-coverage[11.0.5]. - phpunit/phpunit 11.2.7 requires sebastian/diff ^6.0.2 -> satisfiable by sebastian/diff[6.0.2]. - vimeo/psalm[5.12.0, ..., 5.13.1] require php ^7.4 || ~8.0.0 || ~8.1.0 || ~8.2.0 -> your php version (8.3.9) does not satisfy that requirement. - sebastian/diff 3.0.2 requires php ^7.1 -> your php version (8.3.9) does not satisfy that requirement. - sebastian/diff[4.0.0, ..., 4.0.1] require php ^7.3 -> your php version (8.3.9) does not satisfy that requirement. - Root composer.json requires phpunit/phpunit ^11.2.7 -> satisfiable by phpunit/phpunit[11.2.7]. - Root composer.json requires vimeo/psalm ^4.30|^5.12 -> satisfiable by vimeo/psalm[4.30.0, 5.12.0, ..., 5.25.0].