Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires rollbar/rollbar ^4.0 -> satisfiable by rollbar/rollbar[v4.0.0, v4.0.1, v4.0.2]. - rollbar/rollbar[v4.0.0, ..., v4.0.2] require monolog/monolog ^2 || ^3 -> satisfiable by monolog/monolog[dev-main, 2.0.0-beta1, ..., 2.x-dev, 3.0.0-RC1, ..., 3.x-dev (alias of dev-main)] from composer repo (https://repo.packagist.org) but monolog/monolog is the root package and cannot be modified. See https://getcomposer.org/dep-on-root for details and assistance.