Cal. PROB § 8007

(a) Except as provided in subdivision (b), an order admitting a will to probate or appointing a personal representative, when it becomes final, is a conclusive determination of the jurisdiction of the court and cannot be collaterally attacked. (b) Subdivision (a) does not apply in either of the following cases: (1) The presence of extrinsic fraud in the procurement of the court order. (2) The court order is based on the erroneous determination of the decedent’s death.