Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires wyrihaximus/async-test-utilities ^8.0.5 -> satisfiable by wyrihaximus/async-test-utilities[8.0.5]. - roave/infection-static-analysis-plugin[1.36.0, ..., 1.36.x-dev] require infection/infection 0.29.10 -> satisfiable by infection/infection[0.29.10]. - wyrihaximus/async-test-utilities 8.0.5 requires wyrihaximus/test-utilities ^6.0.9 -> satisfiable by wyrihaximus/test-utilities[6.0.9, 6.0.10]. - wyrihaximus/test-utilities[6.0.9, ..., 6.0.10] require infection/infection ^0.27.0 -> satisfiable by infection/infection[0.27.0, ..., 0.27.x-dev]. - Conclusion: install roave/infection-static-analysis-plugin 1.36.0 (conflict analysis result) - You can only install one version of a package, so only one of these can be installed: infection/infection[0.27.0, ..., 0.32.0]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.