Cal. Sts. & High. Code § 9705

If any reassessment or any refunding bond is held illegal or invalid in any action or proceeding upon any ground which would apply to the entire reassessment or the entire issue of refunding bonds, then the unpaid bonds refunded remain in full force and effect. If the unpaid bonds have been canceled, the treasurer of the city which conducted the invalid refunding or reassessment proceedings shall issue new bonds of the same tenor, force, and effect as the canceled unpaid bonds.