Your lock file does not contain a compatible set of packages. Please run composer update. Problem 1 - symfony/translation-contracts is locked to version v1.10.0 and an update of this package was not requested. - symfony/translation-contracts v1.10.0 requires php >=7.1.3 -> your php version (5.6; overridden via config.platform, actual: 5.6.40) does not satisfy that requirement.