How do I upgrade Magento 2 EE using composer

Question

I am trying to upgrade Magento 2 EE using composer but I keep getting this message whenever I run composer update/upgarde

- The requested package magento/product-enterprise-edition 2.2.3 exists as magento/product-enterprise-edition[2.1.9] but these are rejected by your constraint.

I have the correct keys to download the latest version using composer but would like to know what this message means so that I can resolve it?

Does anyone know what the message is referring to? Is the constraint based on a dependency in the codebase or the Magento account itself?

Edit: running composer require magento/product-enterprise-edition 2.2.3 --no-update

I get the following response:

  [InvalidArgumentException]                                                                                                                                                                    
  Could not find a matching version of package magento/product-enterprise-edition. Check the package spelling, your version constraint and that the package is available in a stability which   
  matches your minimum-stability (alpha).  

Answer 1

1. Connect you via SSH in the root of you Magento

2. The method is : composer require <product> <version> --no-update, so according to your version you have to run this:

composer require magento/product-enterprise-edition 2.2.3 --no-update

3. rm -rf /generated
   rm -rf /var/cache/
   rm -rf /var/page_cache/
   
   php bin/magento setup:upgrade
   php bin/magento setup:di:compile
   php bin/magento indexer:reindex
   

More informations in Magento DevDocs