Wilton J. Morgan, Jr., appeals his sentence for possession of a firearm by a convicted felon in violation of 18 U.S.C. § 922(g)(1). Morgan argues that the district court committed reversible error under United States v. Booker, 543 U.S. 220, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005), by sentencing him pursuant to a mandatory application of the Sentencing Guidelines. Because the district court at sentencing addressed Blakely v. Washington, 542 U.S. 296, 124 S.Ct. 2531, 159 L.Ed.2d 403 (2004), in the context of the Sentencing Guidelines, we review the district court’s “Fanfan” error under the harmless error standard of review. See United States v. Rodriguez, 15 F.3d 408, 414 (5th Cir. 1994); see United States v. Rodriguez-Mesa, 443 F.3d 397, 404 (5th Cir. 2006). The Government has not shown beyond a reasonable doubt that the error was harmless. See United States v. Walters, 418 F.3d 461, 463-64 (5th Cir. 2005). Accordingly, Morgan’s sentence is vacated, and this case is remanded for resentencing.

Although Morgan has been released from custody, his Aoofcer-based challenge of his sentence is not moot. See United States v. Johnson, 529 U.S. 53, 60, 120 S.Ct. 1114, 146 L.Ed.2d 39 (2000) (recognizing that trial court may modify an individual’s conditions of supervised release at any time after one year under 18 U.S.C. § 3583(e)(1) if warranted by conduct of defendant and interests of justice). We neither express nor intimate any view as to whether the terms of Morgan’s supervised release should be modified.

The sentence is VACATED and case REMANDED FOR RESENTENCING.