OPINION OF THE COURT
Armаndo Leyva was convicted in Phila-, delphia’s Court of Common Pleas of statutory sexual assault and corruption of a minor. Leyva, who was thirty-five years old at the time, had engaged in a six-month sexual relationship with a teenage girl who attended his church. He was sentenced to eleven-and-a-half to twenty-three months in prison, followed by three years of probation.
Represented by new appellate counsel, Leyva sought direct and collateral state court review of his conviction, asserting various claims of ineffective assistance of trial counsel. Among these claims, Leyva contended that trial counsel had a conflict of interest arising from his former representation of the complainant’s mother’s ex-boyfriend. He also claimed that trial counsel had received an offer from the complainant’s mother to drop the charges against Leyva in exchange for $5,000. According to Leyva, trial counsel was ineffective for failing to withdraw his representation in order to testify about these facts. Pennsylvania’s courts denied review of some of Leyva’s claims because he failed to submit affidavits that trial counsel or the complainant’s mother were “available and willing” to testify; they declined to review other claims aftеr Leyva was released from custody.
Leyva raised his ineffectiveness claims in a federal petition for habeas corpus. The District Court dismissed the petition after concluding that Leyva’s failure to comply with Pennsylvania’s procedural requirements constituted a procedural bar to federal review. Because we disagree, we will vacate and remand for further proceedings.
I. Factual and Procedural Background
On July 21, 1999, Armando Leyva was tried before a judge in Philadelphia’s Court of Common Pleas on charges of involuntary deviate sexual intercourse, statutory sexual assault, corruption of a minor, and indecent assault. 1 The prosecution’s principal witness at trial was an adolescent girl, L.B., who attended the church where Leyva was an organist. According to her testimony, during the first six months of 1998, when she was fourteen years old, the two carried on a consensual sexual relationship. According to Leyva, the two had never engaged in any sexual conduct.
A central issue at trial was L.B.’s credibility. During cross-examination, Leyva’s attorney attempted to introduce evidence of a “previous perjury.” App. 235. Specifically, he questioned L.B. about a prior accusation of sexual assault she had made against Wilfredo Lopez (her mother’s former boyfriend), but later recanted. Lopez, it came to light, had been represented by Leyva’s attorney at the time of the accusation, so the attorney was familiar with the surrounding facts. He questioned L.B. about whether she was pressured by her mother into making the accusation against Lopez. L.B. maintained the accusation had been truthful, explaining that she later recanted it because she was afraid of Lopez, and because Leyva’s at *361 torney asked her to say “nothing happened.” App. 257, 253.
At the conclusion of trial, the judge found Leyva guilty of statutory sexual assault and corruption of a minor, in violation of 18 Pa. Stat. §§ 3122.1 and 6301, respectively. Because of the evidence about L.B.’s recanted accusation, the judge gave Leyva “the benefit of the doubt as far as involuntary deviate sexual intercourse is concerned,” finding him not guilty of that more serious offense. App. 305. 2 On September 16, 1999, he sentenced Leyva to eleven-and-a-half to twenty-three months in prison, followed by three years’ probation.
On appeal, Leyva retained a new attorney who submitted to the trial court a statement of matters complained of on appeal, as required under Pennsylvania Rule of Appellate Procedure 1925(b). Notably, he included an affidavit from Leyva’s wife stating that trial counsel told her and Ley-va that L.B.’s mother offered to drop thе charges against Leyva in exchange for $5,000. 3 In response, the trial judge issued an opinion concluding that Leyva’s claims of ineffectiveness warranted a new trial. This opinion was without effect, however, because the case was already on appeal before the Superior Court. 4
On appeal, Leyva argued that trial counsel was ineffective for: failing to interview several potential witnesses; failing to withdraw based on a conflict of interest because of his prior representation of Lopez; failing to present L.B.’s mother as a witness; and failing to withdraw from representing Leyva in order to testify at trial.
On October 17, 2002, the Superior Court affirmed Leyva’s conviction. The court disposed of Leyva’s first two claims on the merits, concluding that neither trial counsel’s failure to interview the witnesses identified by Leyva, nor the alleged conflict of interest constituted error or prejudiced Leyva. Regarding Leyva’s second two claims, the court declined to reach them on the merits, concluding that Leyva had failed to present affidavits indicating that L.B.’s mother or Leyva’s trial counsel would have testified. 5
Leyva petitioned for reconsideration, and shortly thereafter petitioned the Pennsylvania Supreme Court for allowance of apрeal. Both petitions were denied. On August 5, 2004 — four days before the expiration of his probation — Leyva filed a petition for collateral relief under Pennsylvania’s Post Conviction Relief Act (“PCRA”), raising additional claims of ineffective assistance of counsel. A few months later, however, the Court of Common Pleas summarily dismissed the PCRA petition because Leyva was no longer in custody.
*362 On the same day that Leyva filed his PCRA petition, he also filed a petition for habeas corpus in federal court. His petition raised five grounds for relief:
(1) Trial counsel was ineffective because he (a) failed to withdraw in order to testify about the efforts of L.B.’s mother to obtain $5,000 from Leyva in exchange for dropping all the charges against him, and (b) failed to call L.B.’s mother as an adverse witness.
(2) Trial counsel was ineffective for (a) failing to withdraw his representation in order to testify after L.B. stated at trial that she was pressured by trial counsel to drop the charges against Lopez, and (b) having a conflict of interest because he previously represented Lopez.
(23) Trial counsel was ineffective and had a conflict of interest because he failed to present evidence that LJB.’s mother was motivated to lie (and to pressure her daughter to lie) because she wаs cooperating with the government in an unrelated case.
(4) Trial counsel was ineffective for failing to request evidence of L.B.’s mother’s cooperation agreement with the government in an unrelated case. Moreover, the government’s failure to turn over this evidence rendered his conviction unconstitutional.
(5) Trial counsel was ineffective for failing to introduce evidence about L.B.’s previous accusation against Jose Rojas.
App. 613-14.
The District Court referred Leyva’s petition to a Magistrate Judge, who recommended denying relief for three reasons.
Leyva v. Williams,
Leyva did not object to the Magistrate Judge’s report and recommеndation, and the District Court adopted it in full. On November 14, 2005, we granted a certificate of appealability, requesting that Ley-va address whether his claims had been procedurally defaulted.
II. Jurisdiction and Standard of Review
A. Jurisdiction
A federal court has jurisdiction to entertain a habeas petition under 28 U.S.C. § 2254(a) “only if [a petitioner] is in custody in violation of the constitution or federal law.”
DeFoy v. McCullough,
393
*363
F.3d 439, 441 (3d Cir.2005);
see also Obado v. New Jersey,
Although Leyva was in custody when he filed his habeas petition, he no longer is. After a petitioner’s release from custody, we consider his habeas case moot unless he “can demonstrate he will suffer some collateral consequences if his conviction is allowed tо stand.”
DeFoy,
In this case, the government does not dispute that Leyva would suffer collateral consequences should his criminal conviction be allowed to stand. Presuming such consequences, we conclude that the District Court had jurisdiction pursuant to 28 U.S.C. §§ 2241 and 2254, and that we have jurisdiction under 28 U.S.C. §§ 1291 and 2253.
See Jacobs v. Horn,
B. Standard of Review
When a district court rules on a habeas petition without an evidentiary hearing, our review is plenary.
Id.
The government argues, however, that we should review only for “plain error,” because Leyva failed to object to the Magistrate Judge’s report and recommendation.
7
In
Nara v. Frank,
we held that “plain error review [rather than
de novo
review] is appropriate where a party fails to timely object to a magistrate judge’s [report and recommendation] in habeas corpus cases.”
In Nara, a magistrate judge issued a report recommending the district court grant a рetition for habeas corpus. The recommendation gave the parties ten days in which to file objections to its determina *364 tions, warning that a “[failure to file timely objections may constitute a waiver of any appellate rights.” Id. at 193. The government failed to object, and the district court adopted the recommendation. Id. Over two weeks later, the government requested that the District Court vacate the order on the grounds that it never received the Magistrate’s report and recommendation. Id. Before the District Court could rule on the request, the government appealed to this Court.
On appeal, we apрlied plain error review, explaining that this standard of review would “promote[] the effectiveness and efficiency of the lower courts by compelling parties to promptly contest disposi-tive issues before the magistrate judge and district judge.” Id. at 196. We also observed that the standard “affordfed] some level of appellate review to all dispositive legal issues raised by a [report and recommendation],” but “g[a]ve substance to the oft-repeated warning that ‘failure to timely object may risk the loss of appellate rights.’ ” Id. at 196-97.
In spite of Nara’s general rule, we decline to apply plain error review in this case. In Nara, the government was proceeding with counsel and had received a clear warning from the magistrate judge that “[fjailure to file timely objections may constitute a waiver of any appellate rights.” Id. at 193. In contrast, there is no indication that Leyva, a pro se litigant, was ever warned that his failure to object to the Magistrate Judge’s report would result in the forfeiture of his rights. 8
Without such a warning, we believe it would be inequitable to deny a
pro se
litigant
de novo
appellate review.
Cf. Welch v. Heckler,
In particular, many jurisdictions provide an exception to the waiver of appellate rights when a magistrate judge fails to inform a
pro se
litigant of the consequences of failing to object.
See Moore v. United States,
In sum, it would be inequitable to apply plain error review, which is extremely limited, to the claims of a pro se litigant who was not warned of the consequences of failing to object. We will therefore review Leyva’s claims de novo.
III. Discussion
On аppeal, Leyva challenges the Magistrate Judge’s determinations that most of his claims were procedurally defaulted, as well as her merits ruling on part of his conflict of interest claim. As set forth further below, we reach the following conclusions. First, Leyva’s failure to submit an affidavit to establish that his trial counsel or the complainant’s mother were available and willing to testify does not result in procedural default of claim 1, because an affidavit requirement is not an “adequate” state ground. Second, Leyva’s failure to comply with Pennsylvania’s custody requirement does not bar review of claims 2(a), 3, and 4, because Leyva’s nonсompliance with this requirement did not result from any failure on his part. Finally, we agree with the government that claim 2(b), concerning trial counsel’s prior representation of Wilfredo Lopez, was properly denied by the Magistrate Judge on the merits. 9
After briefly laying out the applicable habeas jurisprudence, we will address each of our three bases for this decision.
A. Procedural Default
A federal court may not grant a writ of habeas corpus under § 2254 unless the petitioner has “exhausted the remedies available in the courts of the State.” 28 U.S.C. § 2254(b)(1)(A). To do so, a petitioner must “ ‘fairly present’ all federal claims to the highest state court before bringing them in fеderal court.”
Stevens v. Delaware Corr. Ctr.,
Even when a petitioner properly exhausts a claim, however, a federal court may not review it on the merits if a state court’s decision rests on a violation of a state procedural rule.
Johnson v. Pinchak,
A state rule is “adequate” for procedural default purposes if it was “firmly established, readily ascertainable, and regularly followed at the time of the purported default.”
Szuchon v. Lehman,
Finally, if a federal court determines that a claim has been defaulted, it may excuse the default only upоn a showing of “cause and prejudice” or a “fundamental miscarriage of justice.”
Lines v. Larkins,
B. The Affidavit Rule
Leyva alleged that trial counsel was ineffective for failing to present evidence that L.B.’s mother offered to drop the charges against him in exchange for $5,000. According to Leyva, this evidence would have undermined the credibility of the proseсution’s chief witness at trial, and his attorney should have withdrawn in order to testify about the illicit offer. The Pennsylvania Superior Court declined to hear this claim on the grounds that Leyva had failed to submit an affidavit stating that trial counsel would have been “available and willing” to testify. 11
In denying Leyva’s claim, the Superior Court relied on
Commonwealth v. Khalil,
*367
The Superior Court’s reliance on
Khalil
in dismissing Leyva’s claim does not constitute a basis for procedural default. An affidavit rule was neither firmly established nor regularly applied at the time of Leyva’s purported default. As Leyva points out,
Khalil
was issued on August 2, 2002, approximately seven months after he filed his appellate brief. When Leyva filed his appeal — at which point he would have been required to submit affidavits — Pennsylvania’s courts did not require a defendant to submit affidavits.
See Doctor v. Walters,
Our review of precedent at that time reveals no such requirement. For example,
Khalil
relied on
Commonwealth v. Davis,
(1) the witness existed; (2) the witness was available; (3) counsel was informed of the existence of the witness or counsel should otherwise have known of him; (4) the witness was prepared to cooperate and testify for appellant at trial; and (5) the absence of testimony prejudiced appellant so as to deny him a fair trial.
Id. at 111. The Davis court noted that no affidavits, or other evidence, had been presented in support of the availability of most of the defendant’s witnesses. It therefore dismissed the claims relating to those witnesses. As Leyva correctly points out, however, Davis “did not rule that affidavits were the only manner in which the five requirements could be met,” Leyva’s Br. at 22. In other words, the decision left open the possibility of other forms of proof.
Other Superior Court decisions preceding
Khalil
suggest that an affidavit was not the only form of proof that could be offered for a missing witness claim. In
Commonwealth v. Fink,
the court stated that “to establish ineffectiveness for failing to call witnesses, a defendant must
illustrate
that the witnesses were available.”
Furthermore, a few years before Ley-va’s appeal, the Supreme Court of Pennsylvania rejected a missing witness claim when the defendant failed to “set forth the name of a single person who was willing to testify” either “by affidavit
or otherwise.” Commonwealth v. Copenhefer,
In sum, the Superior Court denied review of Leyva’s claims because he failed to submit an affidavit from trial counsel. Based on the foregoing, Leyva did not have “fair notice of the need” to do so in presenting his appeal.
Bronshtein,
C. The Custody Requirement
The Magistrate Judge declined to reach the merits of claims 2(a), 3, and 4, because of procedural default. As the Magistrate Judge explained, these claims were not raised on direct appeal in the state coux'ts, but were x'aised in Leyva’s PCRA petition. The PCRA court dismissed this petition without a review on the merits when Leyva’s term of probation ended because he had failed to comply with the state law requirement that he be “currently serving a sentence.”
See
42 Pa. Stat. § 9543(a)(1)® (“To be eligible for relief ... the petitioner must plead and prove ... that the petitioner ... is at the time relief is grantеd ... currently serving a sentence of imprisonment, probation or parole for the crime.”);
Commonwealth v. Ahlborn, 548
Pa. 544,
Leyva argues that his noncompliance with Pennsylvania’s custody requirement should not bar federal review of his claims. Specifically, he argues that the x'equirement does not create a procedural bar, but simply deprives him of “available State corrective process” under § 2254(b). We have explained, however, that the absence of state corrective process is generally an excuse to the
exhaustion
requirement,
see, e.g., Parker v. Kelchner,
This is not required here. Noncompliance with Pennsylvania’s custody requirement did not result from any
failure
on the рart Leyva, but simply from the expiration of his sentence. This factor was outside Leyva’s control and need not form the basis for a default.
See Williams v. Taylor,
Even if there had been a default, however, we would excuse noncompliance with the custody requirement because Leyva has shown “cause and prejudice.” As we have explained, there is “cause” for noncompliance with a state rule, when “some objective factor external to the defense impeded ... efforts to comply with the ... rule.”
Slutzker,
Moreover, Leyva can sufficiently show the prejudice needed to excuse a procedural default.
Slutzker,
We thus conclude that Leyva’s claims are not defaulted on account of his failure to be in custody.
D. Conflict of Interest
Within his second habeas claim, Leyva alleged that trial counsel represented him in spite of a conflict of interest created by his former representation of L.B.’s mother’s boyfriend, Wilfredo Lopez. The Pennsylvania Superior Court rejected this claim, explaining that trial counsel’s “representation of Lopez, in an unrelated matter, concluded three years before [Ley-va’s] trial” and only provided him additional information about L.B.; it thereby did not constitute a conflict that was prejudicial to Leyva. App. 364. The Magistrate
*370
Judge determined that this ruling was not “contrary to or an unreasonable application of clearly established federal law.”
Leyva,
Leyva does not attempt to rebut this determination, and nowhere points out how trial counsel “actively represented conflicting interests” in a way that “adversely affected [his] performance.”
Hess v. Mazurkiewicz,
IV. Conclusion
We сonclude that neither the affidavit rule nor the custody requirement bar consideration of Leyva’s claims on the merits. Accordingly, we vacate the dismissal of claims 1, 2(a), 3, and 4. Because the merits of these claims have not been briefed or argued before us, we will remand to the District Court for further proceedings.
Notes
. Leyva waived his right to trial by jury.
. He also found Leyva not guilty of indecent assault.
. Leyva also submitted an affidavit from Jose Rojas, who stated he had previously been wrongly accused by L.B. of sexual assault.
. Under Pennsylvania Rule of Appellate Procedure 1925 (amended July 25, 2007), a trial court must issue an opinion providing the reasons for an order, or any rulings or other matters complained of on appеal. According to the Pennsylvania Superior Court, "[wjhen a trial court prepares a Rule 1925 opinion, it no longer has the jurisdiction to grant or deny a defendant’s motion for a new trial. Rather, the court can only explain its trial and post-trial actions in the Rule 1925 opinion.”
Commonwealth v. Clinton,
.As discussed below, this decision was based on the court’s reading of
Commonwealth v. Khalil,
. The Magistrate Judge also found that Ley-va’s procedural default could not be excused because, ”[t]hough petitioner has alleged cause and prejudice for this default, he has not shown that the court’s failure to consider this claim would result in a fundamental miscarriage of justice.’’
Leyva v. Williams,
No. Civ.A. 04-3697,
. Under Rule 8(b) of the Rules Governing Section 2254 Cases, "a district court is not required to determine
de novo
whether a magistrate judge erred ... in his or her report and recommendation if no objection was made by a party on that ground.”
Medina v. Diguglielmo,
. In
Nara,
we distinguished between "failing to timely assert" a right, which results in "forfeiture" (and therefore plain error review), and "waiver" of a right, which “extinguishes any error.”
Nara v. Frank,
. Leyva does not address the Magistrate’s dismissal of claim 5, and we assume he has conceded that it was properly dismissed.
See United States v. Voigt,
. In assessing adequacy, we consider whether: "(1) the state procedural rule speaks in unmistakable terms; (2) all state appellate courts refused to review the petitioner’s claims on the merits; and (3) the state courts' refusal in this instance is consistent with other decisions.”
Jacobs v. Horn,
. On this same ground, the Superior Court declined to consider Leyva's ineffectiveness claim for failure tо call L.B.’s mother.
.According to the court, an affidavit is:
[a] statement in writing of a fact or facts signed by the party making it, sworn to or affirmed before an officer authorized by the laws of this Commonwealth to take acknowledgments of deeds, or authorized to administer oaths, or before the particular officer or individual designated by law as the one before whom it is to or may be taken, and officially certified to in the case of an officer under his seal of office.
Khalil,
. Even the government concedes that an affidavit is not required and that "the actual rule is not so rigid or inflexible.” Gvt. Br. at 27.
. Leyva contends that he sufficiently demonstrated that trial counsel was available tо testify under Pennsylvania law. We do not consider whether his proffer was sufficient to meet Pennsylvania's procedural requirement for bringing his claim, however, but limit our review to the state court’s basis for dismissal, which was the affidavit requirement.
.
Cf. Albrecht v. Horn,
.Pennsylvania's custody requirement for hearing PCRA claims is more stringent than the federal jurisdictional requirement for ha-beas corpus. In determining whether a petitioner is "in custody,” federal law looks to the date the petition is filed,
Barry v. Bergen County Probation Dept.,
