Reinstall the Magento software
A contributing developer reinstalls Magento by updating composer.json to specify the Magento product version and component versions desired and runs composer update.
To reinstall the Magento software as a contributing developer:
- Log in to your Magento server as a user with permissions to modify files in the Magento file system (for example, the switch to the file system owner.
- 
    Make a backup copy of composer.jsonin your Magento installation directory:1 cd <magento_root>1 cp composer.json composer.json.bak
- Open composer.jsonin a text editor.
- 
    Locate the following line: 1 2 3 "require": { "magento/product-community-edition": "<version>" }, 
- 
    Replace <version>with the version to which you want to upgrade, where<version>is the product version to use.(The product version is in the format 2.0.x)
.
- Save your changes to composer.jsonand exit the text editor.
- 
    Enter the following command: 1 composer update Wait for dependencies to update. 
- Install the Magento software.