QML (and QtQuick) versioning is not the same as Qt versioning. This is understandably confusing for some people, so let me take the long-form approach and describe the what, why and how of QML versioning. Note: This is the essay version. The technical version with code snippets is in the docs where it should be. As an essay version it’s mostly “why”, for better answers to “what” clone the repository and look at the examples. For better answers to how clone and read the source code for the engine; qqmlengine.cpp contains fewer lines than this blog post 😉 .