Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpcompatibility/php-compatibility dev-develop -> satisfiable by phpcompatibility/php-compatibility[dev-develop]. - phpcompatibility/php-compatibility dev-develop requires squizlabs/php_codesniffer ^4.0.1 -> found squizlabs/php_codesniffer[4.0.1] but it conflicts with your root composer.json require (^3.13.3). Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.