Your requirements could not be resolved to an installable set of packages. Problem 1 - 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 ~0.12.1 -> found wp-cli/php-cli-tools[v0.12.1] but the package is fixed to v0.11.22 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command. Problem 2 - wp-cli/cache-command is locked to version v2.1.3 and an update of this package was not requested. - wp-cli/cache-command v2.1.3 requires wp-cli/wp-cli ^2.5 -> satisfiable by wp-cli/wp-cli[2.12.x-dev (alias of dev-main)]. - wp-cli/wp-cli dev-main requires wp-cli/php-cli-tools ~0.12.1 -> found wp-cli/php-cli-tools[v0.12.1] but the package is fixed to v0.11.22 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command. - wp-cli/wp-cli 2.12.x-dev is an alias of wp-cli/wp-cli dev-main and thus requires it to be installed too. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.