ppy/osu · error · InvalidOperationException

Cannot Update a scale operation without calling Begin first!

Error message

Cannot Update a scale operation without calling Begin first!

What it means

OsuSelectionScaleHandler.Update() applies a scale delta using objectsInScale, defaultOrigin, and OriginalSurroundingQuad, which are populated by Begin(). Without Begin, these are null. The guard throws before the Debug.Assert on nulls would fire.

Solutions

Ensure Begin() is called before any Update() in the scale lifecycle.
Guard Update calls behind an OperationInProgress.Value check.

Example fix

// before
scaleHandler.Update(deltaScale); // called before Begin

// after
if (scaleHandler.OperationInProgress.Value)
    scaleHandler.Update(deltaScale);

Defensive patterns

Strategy: validation

Validate before calling

// Guard Update against calls before Begin
if (scaleHandler.OperationInProgress.Value)
    scaleHandler.Update(deltaScale, origin, adjustAxis, axisRotation);

Prevention

Route all Update calls through an OperationInProgress.Value guard.
Ensure event subscriptions are cleared on Commit to prevent stale callbacks.

When it happens

Trigger: Calling Update(scale, origin, adjustAxis, axisRotation) before Begin() has been called.

Common situations: Input event ordering issues where the scale delta handler runs before initialization; state desync between the UI scale control and the handler's OperationInProgress.

Related errors

AI-assisted analysis of ppy/osu@d9c73e12ad (2026-08-13). Data as JSON: /api/errors/df4168be64794d5d. Report an issue: GitHub.

Appendix: source

Thrown at osu.Game.Rulesets.Osu/Edit/OsuSelectionScaleHandler.cs:103

        public override void Begin()
        {
            if (OperationInProgress.Value)
                throw new InvalidOperationException($"Cannot {nameof(Begin)} a scale operation while another is in progress!");

            base.Begin();

            changeHandler?.BeginChange();

            objectsInScale = selectedMovableObjects.ToDictionary(ho => ho, ho => new OriginalHitObjectState(ho));
            OriginalSurroundingQuad = GeometryUtils.GetSurroundingQuad(objectsInScale.Keys);
            originalConvexHull = GeometryUtils.GetConvexHull(objectsInScale.Keys);
            defaultOrigin = GeometryUtils.MinimumEnclosingCircle(originalConvexHull).Item1;
        }

        public override void Update(Vector2 scale, Vector2? origin = null, Axes adjustAxis = Axes.Both, float axisRotation = 0)
        {
            if (!OperationInProgress.Value)
                throw new InvalidOperationException($"Cannot {nameof(Update)} a scale operation without calling {nameof(Begin)} first!");

            Debug.Assert(objectsInScale != null && defaultOrigin != null && OriginalSurroundingQuad != null);

            Vector2 actualOrigin = origin ?? defaultOrigin.Value;
            scale = clampScaleToAdjustAxis(scale, adjustAxis);

            // for the time being, allow resizing of slider paths only if the slider is
            // the only hit object selected. with a group selection, it's likely the user
            // is not looking to change the duration of the slider but expand the whole pattern.
            if (objectsInScale.Count == 1 && objectsInScale.First().Key is Slider slider)
            {
                scaleSlider(slider, scale, actualOrigin, objectsInScale[slider], axisRotation);
            }
            else
            {
                scale = ClampScaleToPlayfieldBounds(scale, actualOrigin, adjustAxis, axisRotation);

                foreach (var (ho, originalState) in objectsInScale)

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