All contracts, agreements or other obligations entered into, all ordinances passed, and resolutions and orders adopted, contrary to the preceding sections, shall be void, and no person whatever shall have any claim or demand against the city thereunder, nor shall the council, or any officer of the city, waive or qualify the limits fixed by any ordinance, resolution or order, as provided in section 9 of this chapter of the Charter, or fasten upon the city any liability whatever, in excess of such limits, or relive any party from an exact compliance with his contract under such ordinance, resolution or order; provided, that this section shall not apply in case of public disaster calling for extraordinary emergency expenditure.