No omission, informality or irregularity in the proceedings in, or preliminary to, the making of any special assessment shall affect the validity of the same, where the assessment roll has been confirmed by the governing authorities. The assessment roll and the record thereof kept by the city clerk shall be competent and sufficient evidence that the assessment was duly levied and the assessment rolls duly made and adopted, and that all other proceedings incident to the adoption of said assessment roll were duly had, taken and performed as required by this chapter. However, no assessment shall be valid and legal unless the notice required by this chapter shall have been given.
