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]. - infection/infection 0.27.10 requires justinrainbow/json-schema ^5.2.10 -> satisfiable by justinrainbow/json-schema[5.2.10, ..., 5.x-dev]. - 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 6.0.10 requires infection/infection ^0.27.0 -> satisfiable by infection/infection[0.27.0, ..., 0.27.x-dev]. - Conclusion: don't install justinrainbow/json-schema 5.2.10 (conflict analysis result) - Conclusion: don't install infection/infection 0.27.0 (conflict analysis result) - Conclusion: don't install infection/infection 0.27.7 (conflict analysis result) - Conclusion: don't install infection/infection 0.27.8 (conflict analysis result) - Conclusion: don't install wyrihaximus/test-utilities 6.0.9 (conflict analysis result) - Conclusion: install justinrainbow/json-schema 6.6.3 (conflict analysis result) - You can only install one version of a package, so only one of these can be installed: justinrainbow/json-schema[5.2.10, ..., 5.x-dev, 6.0.0-beta, ..., 6.6.4]. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.