No existing judgment or decree quieting title to real estate as against defects arising prior to January 1, 1966, and purporting to sustain the record title shall be held ineffectual because of the failure to properly set out in the petition or notice the derivation or devolution of the interest of the unknown defendants, or on account of the failure of the record to show that such notice was approved by the court or that the same was published as directed by the court, or because of the failure of the record to show that an affidavit was filed by plaintiff showing that personal service could not be made on any defendant in the state of Iowa, or because of the failure of defense by a guardian ad litem for any defendant under legal disability, or where there was more than one tract of real estate described in the same petition and decree, or where the plaintiffs have no joint or common interest in the property or defects of title, or because of failure to comply with any other provision of law. All such decrees are hereby made legal and effectual the same as if all provisions of law had been complied with in obtaining them.