A solution for some cases (at least for mine and hopefully yours :-)) can be found at the end of this post.
After waiting several days since my original post that started this thread (hoping for a solution to be reported), my first attempt at filing this evening (April 21) resulted in the same error as originally and the same as everyone else has been experiencing.
Given that some of the postings talked about farming CCA being a possible trigger, I went to have a look and noticed that Turbotax had calculated and claimed the full amount of available CCA on form TP80. This amount was more CCA than what was required to bring net revenue down to zero. This "error" was present only on the Quebec TP80 form, not on the federal form (T2042). To be clear, the right amount of CCA was calculated on the T2042. The error in the TP80 CCA calculation meant that net farming income on line 264 of TP80 was negative. I had not noticed the error because when the TP80 net income number was reported up through Schedule L and onto Line 164 of TP1, it was zeroed by Turbotax which was what I was expecting.
SOLUTION: I went into the CCA calculation on form TP80 and forced the CCA rate/value to the right number (using F2), the net revenue on line 264 of TP80 went from negative to zero (as expected). NETFILE then worked fine, no error message. Hopefully this will be useful to some of those still experiencing this problem. Good luck!
