How to Upgrade Magento 2
Magento 2 can be simply upgraded, if new actual version is specified in composer.json in both fields version and
and then to execute command
This command will download new core files, but it will fail, if system requirements aren’t satisfied. Composer checks PHP version, that is installed for CLI mode and all required PHP libraries and won’t upgrade Magento, if PHP version is incompatible or there is no required PHP library. Also this command will asks keys, that should be generated on marketplace.magento.com side and it won’t download Magento EE, if it hasn’t been purchased by account, that keys assigned to.
After download new version these commands should be executed
Often execute permissions should be set to file bin/magento after upgrade.