Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires codelicia/xulieta 1.0.x-dev -> satisfiable by codelicia/xulieta[1.0.x-dev]. - phpunit/php-code-coverage 11.0.x-dev is an alias of phpunit/php-code-coverage dev-main and thus requires it to be installed too. - phpunit/php-code-coverage dev-main requires nikic/php-parser ^5.0 -> satisfiable by nikic/php-parser[v5.0.0alpha1, ..., 5.0.x-dev (alias of dev-master)]. - nikic/php-parser 5.0.x-dev is an alias of nikic/php-parser dev-master and thus requires it to be installed too. - phpunit/phpunit dev-main requires phpunit/php-code-coverage ^11.0 -> satisfiable by phpunit/php-code-coverage[11.0.0, 11.0.x-dev (alias of dev-main)]. - You can only install one version of a package, so only one of these can be installed: nikic/php-parser[dev-master, v4.13.2, ..., 4.x-dev, v5.0.0alpha1, v5.0.0alpha2, v5.0.0alpha3]. - phpunit/phpunit 11.0.x-dev is an alias of phpunit/phpunit dev-main and thus requires it to be installed too. - codelicia/xulieta 1.0.x-dev requires nikic/php-parser ^v4.13.2 -> satisfiable by nikic/php-parser[v4.13.2, ..., 4.x-dev]. - Root composer.json requires phpunit/phpunit 11.0.x -> satisfiable by phpunit/phpunit[11.0.0, 11.0.x-dev (alias of dev-main)].