Order of source repository

It is possible to have both TFVC and GIT in the same TFS project, and when you create a new project you set the default repository and the afterwards you can add the second one.
An important notice about this:
If you run XAML based builds, the build definitions can only use the default repository aka the one you selected when you created the TFS project.

So if you still use XAML, make sure you select the correct repository when you create the project

It is not possible to switch over. At least not officially yet….
UPDATE: MS support has a created a tool that can fix this

TFS 2018 released

Yesterday at Connect(), the latest version of TFS was released.
Some of the new things to mention are:
Build-in Wiki for your teams to create a single entry site for help and guides.
Git Forks, so you can have forks on your main branch
Large scale of Git support, what Microsoft calls GVFS, for large scale Git repositories.

TFS 2018 will no longer support XAML based builds and lab management (MTLM lab part).

Full release notes click here TFS 2018 rel notes
Download link for ISO TFS 2018 ISO

More info about the release will come… Stay tuned