Minn. R. Civ. App. P. 131.02
Subdivision 1. Motion for Extension. No extension of the time fixed for the filing of a brief will be granted except upon a motion pursuant to Rule 127 made within the time specified for the filing of the brief. The motion shall be considered by a justice, judge or a person designated by the appellate court, acting as a referee, and shall be granted only for good cause shown.
Subd. 2. Procedure. The date the brief is due shall be stated in the motion. The motion shall be supported by an affidavit which discloses facts showing that with due diligence, and giving reasonable priority to the preparation of the brief, it will not be possible to file the brief on time. All factual statements required by this rule shall be set forth with specificity.
Minn. R. Civ. App. P. 131.02
This rule has been clarified to make explicit that a request for an extension of time to file a brief must be made within the time specified by rule or court order for the filing.