Magento 2 - How to upgrade to magento 2.4.0?

Question

I try to upgrade from 2.3.5-p1 to 2.4.0. I changed the version in composer.json and executed composer update but I get:

Loading composer repositories with package information Updating dependencies (including require-dev) Your requirements could not be resolved to an installable set of packages.

Problem 1 - The requested package magento/product-enterprise-edition 2.4.0 exists as magento/product-enterprise-edition[2.3.4-p2, 2.3.5-p1, 2.3.5, 2.3.3-p1, 2.3.4, 2.2.11, 2.3.2-p2, 2.2.10, 2.3.3, 2.2.9, 2.1.18, 2.3.2, 2.2.8, 2.3.1, 2.1.17, 2.3.0, 2.2.7, 2.1.16, 2.2.6, 2.1.15, 2.1.14, 2.2.5, 2.2.4, 2.1.13, 2.2.3, 2.1.12, 2.0.18, 2.2.2, 2.1.11, 2.1.10, 2.2.1, 2.0.17, 2.2.0, 2.0.16, 2.1.9, 2.2.0-rc30, 2.2.0-rc23, 2.2.0-rc22, 2.2.0-rc21, 2.2.0-rc20, 2.1.8, 2.0.15, 2.0.14, 2.1.7, 2.1.6, 2.0.13, 2.1.5, 2.0.12, 2.1.4, 2.0.11, 2.1.3, 2.1.2, 2.0.10, 2.1.1, 2.0.9, 2.0.8, 2.1.0, 2.1.0-rc3, 2.1.0-rc2, 2.1.0-rc1, 2.0.7, 2.0.6, 2.0.5, 2.0.4, 2.0.3, 2.0.2, 2.0.1, 2.0.0] but these are rejected by your constraint.

Answer 1

For now Magento 2.4 is still in alpha state https://devdocs.magento.com/guides/v2.4/release-notes/bk-release-notes.html