Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires nextcloud/ocp dev-stable26 -> satisfiable by nextcloud/ocp[dev-stable26]. - nextcloud/ocp dev-stable26 requires psr/container ^1.1.1 -> found psr/container[1.1.1, 1.1.2] but the package is fixed to 2.0.2 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command. Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.