A judgment to which a party is procedurally entitled cannot be considered to have been granted erroneously within the meaning of Rule 42(1)(a) merely by reason of facts (including a defense on the merits) of which the judge who granted the judgment was unaware. A court granting default judgment does so on the basis that the defendant has been properly notified as required by the rules, has not defended, and the plaintiff is entitled to the order sought - not on the basis that no defense exists. The existence or non-existence of a defense on the merits is an irrelevant consideration in granting default judgment and, if subsequently disclosed, cannot transform a validly obtained judgment into an erroneous judgment. However, where there is a procedural irregularity (such as lack of proper notice), a judgment may be erroneously granted even if this only becomes apparent from facts not appearing on the original record.