Cal. Sts. & High. Code § 5369

No assessment, warrant, or diagram, and no proceedings prior to the assessment, shall be held invalid by any court for any error, informality, or other defect in the same, where the resolution of intention of the legislative body to do the work, has been actually published as provided in this division. When no appeal is taken or when the orders and determinations of the legislative body upon appeal have been complied with, and the legislative body is satisfied with the correctness of the assessment, the legislative body shall forthwith confirm the proceedings and the assessment and the street superintendent shall attach thereto a warrant bearing the date of such confirmation.