What is "Basis of Partnership Interest" in Part II Line 7? Getting error message looking for input. What is it looking for and where do I find the answer?

The "Basis of Partnership Interest" is what you paid for the investment, less any cash distributions you received plus your share of any income reported on the Schedule K-1s from 2015 and 2016.

The "Basis of Partnership Interest" is what you paid for the investment, less any cash distributions you received plus your share of any income reported on the Schedule K-1s from 2015 and 2016.

Since I've been doing my taxes with TurboTax since 2015, it's frustrating that TurboTax just can't do the math from those previous tax forms.

It's not the responsibility of TT to maintain the basis of a partner's interest in the partnership.

That is the partner's responsibility.