All previous efforts converge in this stage of the project. Almost done! You can plan the implementation to be done overnight or in a weekend, whatever suits your organization best. Now there is a moment of code-freeze. That moment lasts about as long as the implementation itself. All code and data is to be hauled from your source production environment through the factory into the target environment.
A small step in the migration project, a giant leap for your organization.
While this is the final step in the migration of your software, it is the beginning of a new lifespan for your applications. After this phase you can work on renewing your application base using the technology and comfort that comes with the new environment. And simply stay using the mission-critical proven core of your modernized applications.