R.I. Gen. Laws § 44-9-24
The title conveyed by a tax collector's deed shall be absolute after foreclosure of the right of redemption by decree of the superior court as provided in this chapter. Notwithstanding the rules of civil procedure or the provisions of chapter 21 of title 9, no decree shall be vacated except in a separate action instituted within six (6) months following entry of the decree and in no event for any reason, later than six (6) months following the entry of decree. Furthermore, the action to vacate shall only be instituted for inadequacy of notice of the petition amounting to a denial of due process or for the invalidity of the tax sale because the taxes for which the property was sold had been paid or were not due and owing because the property was exempt from the payment of such taxes. The superior court shall have exclusive jurisdiction of the foreclosure of all rights of redemption from titles conveyed by a tax collector's deed, and the foreclosure proceedings shall follow the course of equity in a proceeding provided for in §§ 44-9-25 - 44-9-33.
R.I. Gen. Laws § 44-9-24