Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires infection/infection ^0.26.19 -> satisfiable by infection/infection[0.26.19, 0.26.20, 0.26.21, 0.26.x-dev]. - phpunit/phpunit[11.4.4, ..., 11.5.x-dev] require sebastian/diff ^6.0.2 -> satisfiable by sebastian/diff[6.0.2, 6.0.x-dev]. - Conclusion: don't install sebastian/diff 6.0.2 (conflict analysis result) - Root composer.json requires phpunit/phpunit ^11.4.4 -> satisfiable by phpunit/phpunit[11.4.4, 11.4.x-dev, 11.5.x-dev]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.