Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires oat-sa/extension-tao-mediamanager dev-ab16d3fd0919759b04c2fd0c2b9c2b5e6481dff7 as v99.99.99 -> satisfiable by oat-sa/extension-tao-mediamanager[dev-ab16d3fd0919759b04c2fd0c2b9c2b5e6481dff7]. - oat-sa/extension-tao-mediamanager dev-ab16d3fd0919759b04c2fd0c2b9c2b5e6481dff7 requires oat-sa/generis dev-feat/REL-1723/update-flysystem-lib as 16.0.0 -> satisfiable by oat-sa/generis[dev-feat/REL-1723/update-flysystem-lib]. - oat-sa/extension-tao-mediamanager dev-ab16d3fd0919759b04c2fd0c2b9c2b5e6481dff7 requires oat-sa/tao-core >=54.23.0 -> satisfiable by oat-sa/tao-core[v54.23.0, ..., v54.25.0, 9999999-dev]. - oat-sa/tao-core[dev-master, v54.23.0, ..., v54.25.0] require oat-sa/generis >=15.39.0 -> satisfiable by oat-sa/generis[v15.39.0, v15.39.1, v15.40.0, 9999999-dev]. - You can only install one version of a package, so only one of these can be installed: oat-sa/generis[dev-feat/REL-1723/update-flysystem-lib, dev-master, v14.0.0, ..., v14.4.0, v15.0.0, ..., v15.40.0].