This is a known issue with deploying free apps hosted on Git repositories. It is being worked on.
It does not happen on all Git-hosted apps (/revisions), therefore workarounds such as the one Tim mentioned can work.
A different workaround (which may be easier) is to deploy through Mendix Studio (click "Publish").
Re-download your project from Git and see if you have the same problem when publishing that one. Probably not.
Then reapply the changes you have made. Start with the one you expect is causing the problem. Each time publishing is succesful, commit the change.
I had exactly the same error message as the author. Waiting for solutions~~~