Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires wp-cli/php-cli-tools dev-master as 0.12.x-dev, found wp-cli/php-cli-tools[dev-main, 0.12.x-dev (alias of dev-main)] but it does not match the constraint. Perhaps dev-master was renamed to dev-main? Problem 2 - Root composer.json requires wp-cli/wp-cli dev-main -> satisfiable by wp-cli/wp-cli[dev-main]. - wp-cli/wp-cli dev-main requires wp-cli/php-cli-tools ~0.12.4 -> found wp-cli/php-cli-tools[dev-main, 0.12.x-dev (alias of dev-main)] but it conflicts with your root composer.json require (dev-master as 0.12.x-dev). Problem 3 - Root composer.json requires wp-cli/wp-cli-bundle dev-main -> satisfiable by wp-cli/wp-cli-bundle[dev-main]. - wp-cli/wp-cli-bundle dev-main requires wp-cli/wp-cli dev-main -> satisfiable by wp-cli/wp-cli[dev-main]. - wp-cli/wp-cli dev-main requires wp-cli/php-cli-tools ~0.12.4 -> found wp-cli/php-cli-tools[dev-main, 0.12.x-dev (alias of dev-main)] but it conflicts with your root composer.json require (dev-master as 0.12.x-dev).