Microsoft released the Windows 8 Developer Preview back in September. Last week, the company launched the Windows 8 Consumer Preview which it claimed had over 100,000 changes from the Developer Preview build. That means that any apps that were made for the Developer Preview will need to be updated to run well on the Consumer Preview.
In the newest entry on the official Windows 8 app developer blog site, Microsoft's John Sheehan offers up some hints to developers to make the migration from Developer Preview to Consumer Preview easier. He states:
I can personally assure you that we take every change seriously. Some improvements are made based on direct feedback we hear: a feature is confusing so we make it easier, or it lacks some capability you told us you need. Other times, after we complete a feature and start using it ourselves, we realize it just didn’t land where we wanted it to, so we take what we learned and make it better. There are many factors we consider. Rest assured, we carefully think through every decision, with the goal of creating a great platform for your Metro style apps.
The highly technical blog post goes over how developers can get their Developer Preview app running in the Consumer Preview. Sheehan admits that while it could be tempting to keep your existing project, it's best to start fresh with a new project in Visual Studio. Also if the new new Item Templates support the contracts and features that will be needed in the app, Sheehan says they should be used instead of the app's old code.
Again, the post is mainly for app creators, but if you really want to know more, Microsoft has also released a new document that goes into tons of detail for those that want to covert their older Windows 8 apps to work on the Consumer Preview.