TT is asking me to enter a "business code" for form 3514. The form says I can find this on my Sch C. I do not have a Sch C. How to proceed?

This business code can be found on any of your business activities not only on a Schedule C.  It could refer to a small business, farm income, or a partnership Schedule K-1.  If you do not have a business code, you can enter 999999.

Hope this helps!

I ran into this problem with Turbo Tax Premier 2019.  Just deleting the form fixed it.  For Windows go to <View><Forms> to find form 3514. Use the Delete Form button at the bottom.