Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires oat-sa/extension-tao-backoffice dev-develop as v99.99.99 -> satisfiable by oat-sa/extension-tao-backoffice[dev-develop]. - league/flysystem[3.0.0, ..., 3.x-dev] require php ^8.0.2 -> your php version (7.4.33) does not satisfy that requirement. - oat-sa/extension-tao-backoffice dev-develop requires oat-sa/tao-core >=54.29.1 -> satisfiable by oat-sa/tao-core[v54.29.1, 9999999-dev]. - oat-sa/generis[dev-master, v16.0.0, ..., v16.0.2] require league/flysystem ^3.0 -> satisfiable by league/flysystem[3.0.0, ..., 3.x-dev]. - oat-sa/tao-core[dev-master, v54.29.1] require oat-sa/generis >=16.0.0 -> satisfiable by oat-sa/generis[v16.0.0, v16.0.1, v16.0.2, 9999999-dev].