Neb. Rev. Stat. § 17-201.01: Neb. Rev. Stat. § 17-201.01

When a county board has entered an order declaring any village within the county as incorporated, it shall be conclusively presumed that such incorporation and all proceedings in connection therewith are valid in all respects notwithstanding some defect or defects that may appear on the face of the record, or the absence of any record, unless an action shall be brought within one year from the date of entry of such order of the county board, attacking its validity.