Your requirements could not be resolved to an installable set of packages. Problem 1 - decodelabs/slingshot[v0.1.1, ..., v0.1.8] require decodelabs/archetype ^0.2.21 -> satisfiable by decodelabs/archetype[v0.2.21, v0.2.22]. - decodelabs/slingshot v0.1.9 requires decodelabs/archetype ^0.3 -> satisfiable by decodelabs/archetype[v0.3.0, ..., v0.3.5]. - decodelabs/archetype[v0.2.6, ..., v0.3.5] require decodelabs/veneer ^0.10.10 -> satisfiable by decodelabs/veneer[v0.10.10, ..., v0.10.25] from composer repo (https://repo.packagist.org) but decodelabs/veneer is the root package and cannot be modified. See https://getcomposer.org/dep-on-root for details and assistance. - Root composer.json requires decodelabs/slingshot ^0.1.1 -> satisfiable by decodelabs/slingshot[v0.1.1, ..., v0.1.9].