Mo. Rev. Stat. § 249.600

When any work is done and payment therefor is to be made in special tax bills or in special assessments as provided in sections 249.430 to 249.660, the county shall in no event, nor in any manner whatever, be liable for or on account of such work done or improvement made or liable in any manner for the payment of the same by reason of any invalidity or error in any such tax bill or special assessment.