Frustrated by Magento? Then you’ll love
If you’re trying out Magento’s new Marketplace feature (essentially a ground up redesign, both backend and UX, for Magento Connect), you may run into a 404 error when you try to access the “Web Setup Wizard” (which is where you can access Component Manager, which is what lets you add purchases to your system).
Similar to Magento Connect, both the /setup application and the /update application in Magento 2 are completely separate applications, and their files are physically located in /path/to/magento/setup and /path/to/magento/update. The setup application is actually a separate, stand alone Zend Framework application. The update application looks to be a stand alone script. Both these applications are used during the Component Manager/Marketplace install process.
Since these applications aren’t part of Magento’s standard MVC/MVVM framework, this means if you’re pointing your web root to the /path/to/magento/pub folder, you won’t be able to access them. You’ll need to configure web root to /path/to/magento. Hopefully this is just an oversight in the run up to the launch, and the sort of thing that can be quickly fixed in a future version.