Sts. & Hy. Code, § 35474

Any action or proceeding to set aside, cancel, avoid, annul, or correct any assessment or reassessment, or to review any of the proceedings, acts, or determinations pursuant to this chapter, or to question the validity or enjoin the collection of any assessment or reassessment, or to enjoin the issuance of bonds to represent any assessment or reassessment, shall not be maintained by any person, unless such action or proceeding is commenced within 30 days after the recording of the diagram and assessment or reassessment. Thereafter all persons are barred from any such action or proceeding or any defense of invalidity of the assessment or reassessment, or of bonds issued on the assessment or reassessment.