This is a peculiarity that happens when your spouse does not have his own HSA, just shares your HDHP coverage. As a result, you never answered questions about his HSA (because he doesn't have one) to tell TurboTax the months that he had HDHP coverage in 2017.
At the end of the HSA interview, TurboTax needs to ask "Was [his name] covered by a High Deductible Health Plan (HDHP) in 2016?" to find out if he took advantage of the "last-month" rule in 2016. The last-month rule allows a taxpayer to use the full annual HSA contribution limit, even if the taxpayer was not in the HDHP all year.
When you answered "Family" to that question above and TurboTax did saw that you had not shown his coverage for 2017, the TurboTax assumed that he had a break in coverage.
solution is to just go back to that question and answer "None" if
your spouse at no time in 2016 had an HSA and/or made no contributions to it.
That way, the error message will be skipped and you can continue with your
Thus, when you answered the "What type of HDHP coverage did the spouse have on December 1, 2016?" question with "Self", TurboTax thought that the spouse had coverage in 2016 but none in 2017, so incorrectly assumed that there was a break.
Just answer "none" for your spouse and the break message will go away. The question doesn't apply to your spouse anyway, because it is searching for people who used the last-month rule (as I said above), and since your spouse had no HSA in 2016, he/she could not have made a contribution to it in 2016 using the last-month rule. So "none" will solve your problem and not affect your return.