65 ILCS 5/9-3-38

No collateral attack or litigation shall be instituted which in any way questions the enforceability of the validity of the bonds issued under the provisions of this Division 3 unless such litigation is instituted within 15 days after the issue and delivery of the bonds to the contractor on payment of work, or within 15 days after the issue and delivery thereof to a purchaser, as in this Division 3 provided.