Your requirements could not be resolved to an installable set of packages. Problem 1 - infection/infection[0.26.19, ..., 0.26.21] require sebastian/diff ^3.0.2 || ^4.0 || ^5.0 -> satisfiable by sebastian/diff[3.0.2, 3.0.3, 3.0.4, 4.0.0, ..., 4.0.5, 5.0.0, ..., 5.1.0]. - You can only install one version of a package, so only one of these can be installed: sebastian/diff[3.0.2, 3.0.3, 3.0.4, 4.0.0, ..., 4.0.5, 5.0.0, ..., 5.1.0, 6.0.0]. - phpunit/phpunit 11.0.1 requires sebastian/diff ^6.0 -> satisfiable by sebastian/diff[6.0.0]. - sebastian/diff 3.0.2 requires php ^7.1 -> your php version (8.2.15) does not satisfy that requirement. - sebastian/diff[4.0.0, ..., 4.0.1] require php ^7.3 -> your php version (8.2.15) does not satisfy that requirement. - Root composer.json requires phpunit/phpunit ^11.0.1 -> satisfiable by phpunit/phpunit[11.0.1]. - Root composer.json requires infection/infection ^0.26.19 -> satisfiable by infection/infection[0.26.19, 0.26.20, 0.26.21]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.