This means you have a penalty for late payment of tax. Evidently, Minnesota does not allow you to e-file your return when you have a penalty for late payment of tax. You can attempt to delete schedule M15, as the state will calculate your penalty if you don't list it on the return, as follows:
- Tax tools (on the left menu bar)
- Delete a form
Find schedule M15 in the list and delete the form.
That may allow you to e-file the tax return.