California Code, Government Code - GOV § 66473

A local agency shall disapprove a map for failure to meet or perform any of the requirements or conditions imposed by this division or local ordinance enacted pursuant thereto;  provided that a final map shall be disapproved only for failure to meet or perform requirements or conditions which were applicable to the subdivision at the time of approval of the tentative map;  and provided further that such disapproval shall be accompanied by a finding identifying the requirements or conditions which have not been met or performed.  Such local ordinance shall include, but need not be limited to, a procedure for waiver of the provisions of this section when the failure of the map is the result of a technical and inadvertent error which, in the determination of the local agency, does not materially affect the validity of the map.