S.C. Code Ann. § 58-15-110

No irregularity in complying with the provisions of Sections 58-15-10 to 58-15-100 shall be held to vitiate the corporation until a direct proceeding to set aside and annul the charter be instituted by the proper authority of the State and all acts done and contracts entered into by any such de facto corporation shall have the same force and effect as if no irregularity had existed.