California Code, Health and Safety Code - HSC § 14920

(a) More than once;

(b) Through clerical error;

(c) Through the error or mistake of the board of supervisors or of the officer, board or commission designated by them to give notice or to destroy the weeds, in respect to any material fact, including the case where the cost report rendered and confirmed as hereinbefore provided shows the county abated the weeds but such is not the actual fact;

(d) Illegally;

(e) On property acquired after the lien date by the State or by any county, city, school district or other political subdivision and because of this public ownership not subject to sale for delinquent taxes.