N.Y. Second Class Cities Law § 163
No assessment or tax shall be vacated, set aside, canceled, annulled, reviewed or otherwise questioned or affected by reason of any error, omission, irregularity or defect, not actually fraudulent, in any of the steps or proceedings required to be had or taken as preliminary to, or in the making of, the assessment, or in the levying or collection of the tax, nor in relation to or in connection with any proposal, designation of materials, contract, work or improvement for or on account of which such assessment was made or tax imposed. But all property shall be liable to assessment and all assessments shall be valid and of full force and effect notwithstanding any such error, omission, irregularity or defect.
N.Y. Second Class Cities Law § 163