Your requirements could not be resolved to an installable set of packages. Problem 1 - stefandoorn/sitemap-plugin is present at version dev-sylius2.0 and cannot be modified by Composer - Root composer.json requires sylius/state-machine-abstraction ^1.0 -> satisfiable by sylius/sylius[v1.13.2, ..., v1.13.9], sylius/state-machine-abstraction[v1.13.0, ..., v1.14.1]. - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction * (sylius/sylius v1.13.9 replaces sylius/state-machine-abstraction self.version). - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction * (sylius/sylius v1.13.8 replaces sylius/state-machine-abstraction self.version). - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction * (sylius/sylius v1.13.7 replaces sylius/state-machine-abstraction self.version). - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction * (sylius/sylius v1.13.6 replaces sylius/state-machine-abstraction self.version). - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction * (sylius/sylius v1.13.5 replaces sylius/state-machine-abstraction self.version). - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction * (sylius/sylius v1.13.4 replaces sylius/state-machine-abstraction self.version). - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction * (sylius/sylius v1.13.3 replaces sylius/state-machine-abstraction self.version). - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction * (sylius/sylius v1.13.2 replaces sylius/state-machine-abstraction self.version). - stefandoorn/sitemap-plugin dev-sylius2.0 conflicts with sylius/state-machine-abstraction v1.14.1.