Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires infection/infection ^0.29.8 -> satisfiable by infection/infection[0.29.8, 0.29.9, 0.29.10]. - Root composer.json requires phpunit/phpunit ^12.0.0 -> satisfiable by phpunit/phpunit[12.0.0, 12.0.1, 12.0.2]. - infection/infection 0.29.8 requires sebastian/diff ^3.0.2 || ^4.0 || ^5.0 || ^6.0 -> satisfiable by 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]. - infection/infection 0.29.9 requires thecodingmachine/safe dev-master as 2.5.0 -> found thecodingmachine/safe[dev-master] but it does not match your minimum-stability. - Conclusion: don't install one of sebastian/diff[7.0.0], infection/infection[0.29.10] (conflict analysis result) - Conclusion: install sebastian/diff 7.0.0 (conflict analysis result) - 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, 7.0.0].