Your requirements could not be resolved to an installable set of packages. Problem 1 - sebastian/diff[3.0.0, ..., 3.0.2] require php ^7.1 -> your php version (8.4.0RC1) does not satisfy that requirement. - vimeo/psalm[5.15.0, ..., 5.26.1] require php ^7.4 || ~8.0.0 || ~8.1.0 || ~8.2.0 || ~8.3.0 -> your php version (8.4.0RC1) does not satisfy that requirement. - sebastian/diff[4.0.0, ..., 4.0.1] require php ^7.3 -> your php version (8.4.0RC1) does not satisfy that requirement. - Root composer.json requires phpunit/phpunit ^10.5.38 -> satisfiable by phpunit/phpunit[10.5.38]. - 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]. - You can only install one version of a package, so only one of these can be installed: sebastian/diff[3.0.0, ..., 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 10.5.38 requires sebastian/diff ^5.1.1 -> satisfiable by sebastian/diff[5.1.1]. - Root composer.json requires vimeo/psalm ^4.30.0 || ^5.15 -> satisfiable by vimeo/psalm[4.30.0, 5.15.0, ..., 5.26.1]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.