If the chancellor shall enter a decree confirming and validating said bonds and there shall be no appeal by either party from said decree, or if on appeal the supreme court enters its decree confirming and validating said bonds or other written obligations, the validity of said bonds or other written obligations so issued shall be forever conclusive against the county, municipality, or district issuing same; and the validity of said bonds or other written obligations shall never be called in question in any court in this state.